ci: verify committed generated files are up-to-date

Author: Firestar99

.github/workflows/ci.yaml

@@ -54,6 +54,9 @@ jobs:
         run: cd xtask && cargo build
       - name: xtask generate
         run: cargo xtask generate ${{ matrix.integration }}
+        # if this fails, the files committed don't match what should have been generated
+      - name: generated files are up-to-date
+        run: git add . && git diff --quiet && git diff --cached --quiet
         # no --locked, templates need to generate their lockfile
       - name: cargo fetch
         run: cargo xtask generate ${{ matrix.integration }} -x "cargo fetch --target $TARGET"