chore(ci): bump GitHub Actions to current majors (#237)

* chore(ci): bump GitHub Actions to current majors

Node 20 action runtimes are deprecated on GitHub runners; bump every
first-party action to its latest major across all workflows:

- actions/checkout v4/v6 -> v7
- actions/cache v4 -> v6
- actions/upload-artifact v4 -> v7, download-artifact v4 -> v8
- actions/setup-node v6 -> v7, setup-python v5 -> v7
- actions/upload-pages-artifact v3 -> v5, deploy-pages v4 -> v5

Third-party pins (dtolnay/rust-toolchain, Swatinem/rust-cache,
setup-zig, setup-bun, taiki-e/install-action, maturin-action) are
already on their latest majors.

* chore(ci): pin all actions to full commit SHAs

Mutable @vN tags can be retagged; in the publish workflows that code
runs with OIDC credentials before npm/PyPI/crates.io publishes. Pin
every action (first- and third-party) to its release commit SHA with
the version in a trailing comment.

dtolnay/rust-toolchain infers the toolchain from its ref name, so the
SHA-pinned invocations pass an explicit toolchain: stable input.

.github/workflows/publish-pypi.yml

@@ -24,7 +24,7 @@ jobs:
       published: ${{ steps.check.outputs.published }}
       version: ${{ steps.check.outputs.version }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           fetch-depth: 2
 
@@ -98,21 +98,21 @@ jobs:
           - os: windows-latest
             target: x86_64-pc-windows-msvc
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
         with:
           python-version: '3.12'
 
       - name: Build wheel
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@e83996d129638aa358a18fbd1dfb82f0b0fb5d3b # v1.51.0
         with:
           target: ${{ matrix.target }}
           args: --release --out dist
           manylinux: auto
 
       - name: Upload wheel
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: wheels-${{ matrix.target }}
           path: dist/*.whl
@@ -124,16 +124,16 @@ jobs:
     name: Build sdist
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Build sdist
-        uses: PyO3/maturin-action@v1
+        uses: PyO3/maturin-action@e83996d129638aa358a18fbd1dfb82f0b0fb5d3b # v1.51.0
         with:
           command: sdist
           args: --out dist
 
       - name: Upload sdist
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: sdist
           path: dist/*.tar.gz
@@ -149,7 +149,7 @@ jobs:
       id-token: write
     steps:
       - name: Download all artifacts
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           path: dist
           merge-multiple: true
@@ -158,7 +158,7 @@ jobs:
         run: ls -la dist/
 
       - name: Publish to PyPI
-        uses: pypa/gh-action-pypi-publish@release/v1
+        uses: pypa/gh-action-pypi-publish@dc37677b2e1c63e2034f94d8a5b11f265b73ba33 # release/v1
         with:
           packages-dir: dist
           # Tolerate already-uploaded files so a manual re-run can complete