Downgrade ubuntu

Author: corona10

.github/workflows/build.yml

@@ -486,7 +486,7 @@ jobs:
 
   build_tsan:
     name: 'Thread sanitizer'
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     timeout-minutes: 60
     needs: check_source
     if: needs.check_source.outputs.run_tests == 'true'
@@ -512,7 +512,7 @@ jobs:
 
   build_tsan_free_threading:
     name: 'Thread sanitizer (free-threading)'
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     timeout-minutes: 60
     needs: check_source
     if: needs.check_source.outputs.run_tests == 'true'