Enable armv6 build

We currently do not build the binary for armv6 architecture.
This commit enable `arm-unknown-linux-gnueabihf` target.

Signed-off-by: Rahul Thakoor <rahul@balena.io>

.github/workflows/flowzone.yml

@@ -29,5 +29,6 @@ jobs:
       cargo_targets: |
         aarch64-unknown-linux-gnu,
         armv7-unknown-linux-gnueabihf,
+        arm-unknown-linux-gnueabihf,
         x86_64-unknown-linux-gnu,
         i686-unknown-linux-gnu

Cross.toml

@@ -1,5 +1,8 @@
 [build]
 pre-build = [
     "dpkg --add-architecture $CROSS_DEB_ARCH",
-    "apt-get update && apt-get install --assume-yes libdbus-1-dev:$CROSS_DEB_ARCH"
-]
+    "apt-get update && apt-get install --assume-yes libdbus-1-dev:$CROSS_DEB_ARCH pkg-config:$CROSS_DEB_ARCH"
+]
+
+# [target.arm-unknown-linux-gnueabihf.env]
+# passthrough = ["PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/arm-linux-gnueabihf/lib/:/usr/lib/arm-linux-gnueabihf/:/usr/lib/arm-linux-gnueabihf/pkgconfig/"]