Add MUSL varients of rustup container

.gitea/workflows/publish.yaml

@@ -52,3 +52,13 @@ jobs:
             EXTRA=beta nightly
           file: 'rustup/Dockerfile'
           tags: gitea.loadingm.xyz/the10thwiz/rustup:latest
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          push: true
+          build-args: |
+            TOOLCHAIN=stable
+            EXTRA=beta nightly
+            TARGETS=x86_64-unknown-linux-musl
+          file: 'rustup/Dockerfile'
+          tags: gitea.loadingm.xyz/the10thwiz/rustup:musl-latest

rustup/Dockerfile

@@ -31,3 +31,5 @@ ENV PATH=/root/.cargo/bin:$PATH
 
 ARG EXTRA=""
 RUN for name in "$EXTRA"; do rustup install $name; done
+ARG TARGETS=""
+RUN for name in "$TARGETS"; do rustup target add $name; done