Add snapshot tests in CI

Author: senekor

.github/workflows/snapshot_tests.yml

@@ -0,0 +1,23 @@
+name: Snapshot tests
+on:
+  pull_request
+
+env:
+  # renovate: datasource=github-tags depName=rust lookupName=rust-lang/rust
+  RUST_VERSION: 1.85.1
+
+jobs:
+  snapshot-tests:
+    runs-on: ubuntu-latest
+    if: contains(github.event.pull_request.body, 'RUN_SNAPSHOT_TESTS')
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
+      - run: rustup override set ${{ env.RUST_VERSION }}
+      - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
+
+      - run: git fetch --depth 2
+      - run: git checkout origin/master
+      - name: Generate good snapshots
+        run: INSTA_OUTPUT=none INSTA_UPDATE=always cargo test -- --include-ignored
+      - run: git checkout $GITHUB_SHA # merge of master+branch
+      - run: cargo test -- --include-ignored