Merge pull request #10112 from matrix-org/johannes/ts-strict-checkout-pr

Checkout PR head for strict error checker

.github/workflows/static_analysis.yaml

@@ -52,6 +52,8 @@ jobs:
                     - "--noImplicitAny"
         steps:
             - uses: actions/checkout@v3
+              with:
+                  ref: ${{ github.event.pull_request.head.sha }}
 
             - name: Install Deps
               run: "scripts/ci/layered.sh"