Add support for dynamic musl Python distributions on x86-64 Linux (#12121)

Following the upstream release and #12120, removes gating preventing
installation of the managed musl Python versions.

Of note

- The filtering of musl Python distributions has moved from the Rust
runtime to the metadata fetcher
- The filtering is now conditional on the PBS release date, removing all
old static musl distributions
- We could support the `+static` musl downloads in the future; right
now, they are deprioritized when selecting a variant
- I added test to CI which uses Alpine and installs numpy

Author: zanieb

.github/workflows/ci.yml

@@ -737,6 +737,36 @@ jobs:
           eval "$(./uv generate-shell-completion bash)"
           eval "$(./uvx --generate-shell-completion bash)"
 
+  smoke-test-linux-musl:
+    timeout-minutes: 10
+    needs: build-binary-linux-musl
+    name: "check system | alpine"
+    runs-on: ubuntu-latest
+    container: alpine:latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: "Download binary"
+        uses: actions/download-artifact@v4
+        with:
+          name: uv-linux-musl-${{ github.sha }}
+
+      - name: "Prepare binary"
+        run: |
+          chmod +x ./uv
+          chmod +x ./uvx
+
+      - name: "Smoke test"
+        run: |
+          # Overwrite the 3.13.0 pin from the project, there are not functional
+          # musl distributions for it
+          ./uv python pin 3.13
+          ./uv venv -v
+          ./uv pip install ruff -v
+          ./uvx -v ruff --version
+          ./uv pip install numpy -v
+          ./uv run python -c "import numpy; print(numpy.__version__)"
+
   smoke-test-macos:
     timeout-minutes: 10
     needs: build-binary-macos-x86_64