add verify-msrv workflow

.github/workflows/cargo-msrv.yml

@@ -0,0 +1,24 @@
+name: Verify MSRV
+
+on:
+  push:
+    branches: "**"
+  pull_request:
+    branches: "**"
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  cargo-msrv:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        run: rustup update nightly
+      - name: Set nightly as default
+        run: rustup default nightly
+      - name: Install cargo-msrv
+        uses: taiki-e/install-action@cargo-msrv
+      - name: verify MSRV
+        run: cargo msrv verify