Fix lessopen feature

RawOsString API changed in os_str_bytes 7.0.0 and bat no longer builds
with the lessopen feature because:

- ::from_string() is deprecated and says to use new().
  The documentation says that new(), like from_string() no longer
  needs to copy the string.

- ::assert_from_raw_vec() is no longer merely deprecated and now
  requires selecting the "conversions" feature of os_str_bytes.

Replaces PR#2938

Cargo.toml

@@ -33,7 +33,7 @@ minimal-application = [
 ]
 git = ["git2"] # Support indicating git modifications
 paging = ["shell-words", "grep-cli"] # Support applying a pager on the output
-lessopen = ["run_script", "os_str_bytes"] # Support $LESSOPEN preprocessor
+lessopen = ["run_script", "os_str_bytes/conversions"] # Support $LESSOPEN preprocessor
 build-assets = ["syntect/yaml-load", "syntect/plist-load", "regex", "walkdir"]
 
 # You need to use one of these if you depend on bat as a library:

src/lessopen.rs

@@ -112,7 +112,7 @@ impl LessOpenPreprocessor {
                 }
 
                 (
-                    RawOsString::from_string(lessopen_stdout),
+                    RawOsString::new(lessopen_stdout),
                     path_str.to_string(),
                     OpenedInputKind::OrdinaryFile(path.to_path_buf()),
                 )