[red-knot] mypy_primer: strip ANSI codes

Author: sharkdp

.github/workflows/mypy_primer.yaml

@@ -72,6 +72,12 @@ jobs:
 
           echo ${{ github.event.number }} > pr-number
 
+      - name: "Strip ANSI color codes"
+        uses: justAnotherDev/ansi-color-strip-action@v2
+        with:
+          path: mypy_primer.diff
+          overwrite-path: true
+
       - name: Upload diff
         uses: actions/upload-artifact@v4
         with: