Auto detect msrv.

.github/workflows/update_msrv.yml

@@ -0,0 +1,36 @@
+name: Update MSRV
+
+on:
+  schedule:
+    - cron: '0 0 * * 0'
+  workflow_dispatch:
+
+jobs:
+  runs-on: ubuntu-latest
+  permissions:
+    contents: write
+
+  steps:
+    - uses: actions/checkout@v4
+
+    - name: Setup Rust toolchain
+      uses: actions-rust-lang/setup-rust-toolchain@v1
+      with:
+        toolchain: stable
+
+    - name: Install cargo-msrv
+      run: cargo install cargo-msrv --locked
+
+    - name: Find msrv
+      run: echo "MSRV=$(cargo msrv find --output-format minimal)" >> $GITHUB_ENV
+
+    - name: Set msrv
+      run: cargo msrv set $MSRV
+
+    - name: Update
+      run: |
+        git config user.name 'github-actions[bot]'
+        git config user.email 'github-actions[bot]@users.noreply.github.com'
+        git add Cargo.toml
+        git commit -m "Set MSVC into $(echo $MSVC)"
+        git push