use env var for target

Author: xoviat

.github/workflows/rust.yml

@@ -36,9 +36,10 @@ jobs:
       - name: Run package build
         run: |
           cd build/stm32-bindings
-          cargo fix --lib -p stm32-bindings --target=thumbv8m.main-none-eabihf --allow-no-vcs
-          cargo build --target=thumbv8m.main-none-eabihf
-          cargo package --target=thumbv8m.main-none-eabihf
+          export CARGO_BUILD_TARGET=thumbv8m.main-none-eabihf
+          cargo fix --lib -p stm32-bindings --allow-no-vcs
+          cargo build
+          cargo package
           ls target/package
       - name: Upload package build
         uses: actions/upload-artifact@v4