Merge branch '6.3' into 6.4

* 6.3:
  Use DOCtor-RST 1.53

Author: OskarStark

.github/workflows/ci.yaml

@@ -73,7 +73,7 @@ jobs:
                     key: ${{ runner.os }}-doctor-rst-${{ steps.extract_base_branch.outputs.branch }}
 
             -   name: "Run DOCtor-RST"
-                uses: docker://oskarstark/doctor-rst:1.51.0
+                uses: docker://oskarstark/doctor-rst:1.53.0
                 with:
                     args: --short --error-format=github --cache-file=/github/workspace/.cache/doctor-rst.cache