Add missing i686 alias for x86 (#3899)

This alias is required for the 32-bit x86 manylinux builder.

I've also changed the reporting level for unusable python interpreter
errors to debug so it shows up with `-v`, otherwise we can't see what's
broken:

```console
# uv venv py312 --python python3.12 -vv
    0.000461s DEBUG uv_interpreter::discovery Searching for Python 3.12 in search path
  × No interpreter found for Python 3.12 in search path
```

Reproduction:

```console
$ docker run --rm -it quay.io/pypa/manylinux2014_i686
# curl -LsSf https://astral.sh/uv/install.sh | s
# source $HOME/.cargo/env
# RUST_LOG=trace uv venv py312 --python python3.12
DEBUG Searching for Python 3.12 in search path
TRACE Searching PATH for executables: python3.12, python3, python
TRACE Checking `PATH` directory for interpreters: /root/.cargo/bin
TRACE Checking `PATH` directory for interpreters: /opt/rh/devtoolset-10/root/usr/bin
TRACE Checking `PATH` directory for interpreters: /usr/local/sbin
TRACE Checking `PATH` directory for interpreters: /usr/local/bin
TRACE Found possible Python executable: /usr/local/bin/python3.12
TRACE Querying interpreter executable at /usr/local/bin/python3.12
TRACE Querying Python at `/usr/local/bin/python3.12` did not return the expected data
unknown variant `i686`, expected one of `aarch64`, `armv6l`, `armv7l`, `powerpc64le`, `powerpc64`, `x86`, `x86_64`, `s390x`
--- stdout:
{"result": "success", "markers": {"implementation_name": "cpython", "implementation_version": "3.12.3", "os_name": "posix", "platform_machine": "i686", "platform_python_implementation": "CPython", "platform_release": "6.1.0-10-amd64", "platform_system": "Linux", "platform_version": "#1 SMP PREEMPT_DYNAMIC Debian 6.1.37-1 (2023-07-03)", "python_full_version": "3.12.3", "python_version": "3.12", "sys_platform": "linux"}, "base_prefix": "/opt/_internal/cpython-3.12.3", "base_exec_prefix": "/opt/_internal/cpython-3.12.3", "prefix": "/opt/_internal/cpython-3.12.3", "base_executable": "/usr/local/bin/python3.12", "sys_executable": "/usr/local/bin/python3.12", "sys_path": ["/root/.cache/uv/.tmp7k64ZY", "/opt/_internal/cpython-3.12.3/lib/python312.zip", "/opt/_internal/cpython-3.12.3/lib/python3.12", "/opt/_internal/cpython-3.12.3/lib/python3.12/lib-dynload", "/opt/_internal/cpython-3.12.3/lib/python3.12/site-packages"], "stdlib": "/opt/_internal/cpython-3.12.3/lib/python3.12", "scheme": {"platlib": "/opt/_internal/cpython-3.12.3/lib/python3.12/site-packages", "purelib": "/opt/_internal/cpython-3.12.3/lib/python3.12/site-packages", "include": "/opt/_internal/cpython-3.12.3/include/python3.12", "scripts": "/opt/_internal/cpython-3.12.3/bin", "data": "/opt/_internal/cpython-3.12.3"}, "virtualenv": {"purelib": "lib/python3.12/site-packages", "platlib": "lib/python3.12/site-packages", "include": "include/site/python3.12", "scripts": "bin", "data": ""}, "platform": {"os": {"name": "manylinux", "major": 2, "minor": 17}, "arch": "i686"}, "gil_disabled": false, "pointer_size": "32"}
--- stderr:

---
TRACE Skipping bad interpreter at /usr/local/bin/python3.12
TRACE Checking `PATH` directory for interpreters: /usr/sbin
TRACE Checking `PATH` directory for interpreters: /usr/bin
TRACE Found possible Python executable: /usr/bin/python
TRACE Querying interpreter executable at /usr/bin/python
TRACE Can't use Python at `/usr/bin/python`
TRACE Skipping bad interpreter at /usr/bin/python
TRACE Checking `PATH` directory for interpreters: /sbin
TRACE Checking `PATH` directory for interpreters: /bin
TRACE Found possible Python executable: /bin/python
TRACE Querying interpreter executable at /bin/python
TRACE Can't use Python at `/bin/python`
TRACE Skipping bad interpreter at /bin/python
```

Cargo.toml

@@ -120,7 +120,7 @@ rustc-hash = { version = "1.1.0" }
 same-file = { version = "1.0.6" }
 schemars = { version = "0.8.16", features = ["url"] }
 seahash = { version = "4.1.0" }
-serde = { version = "1.0.197" }
+serde = { version = "1.0.197", features = ["derive"] }
 serde_json = { version = "1.0.114" }
 sha1 = { version = "0.10.6" }
 sha2 = { version = "0.10.8" }

crates/platform-tags/src/platform.rs

@@ -79,7 +79,7 @@ pub enum Arch {
     Armv7L,
     Powerpc64Le,
     Powerpc64,
-    #[serde(alias = "i386")]
+    #[serde(alias = "i386", alias = "i686")]
     X86,
     #[serde(alias = "amd64")]
     X86_64,

crates/uv-interpreter/src/discovery.rs

@@ -375,7 +375,7 @@ fn python_interpreters<'a>(
                     );
                 })
                 .map_err(Error::from)
-                .inspect_err(|err| trace!("{err}")),
+                .inspect_err(|err| debug!("{err}")),
             Err(err) => Err(err),
         })
         .filter(move |result| match result {