Add action to catch semver violations

The main thing is to prevent breaking changes, regardless of the current version specified in Cargo.toml - so we specify `release-type: minor`.

Author: GREsau

.github/workflows/ci.yml

@@ -65,3 +65,12 @@ jobs:
       - uses: dtolnay/rust-toolchain@clippy
       - run: cargo clippy --all-targets -- -D warnings
       - run: cargo clippy --all-targets --all-features -- -D warnings
+
+  semver-checks:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - name: Check semver
+        uses: obi1kenobi/cargo-semver-checks-action@v2
+        with:
+          release-type: minor