Add tags to Windows builds to exclude Gitlab shared runners

Gitlab now has shared Windows runners, which is cool, but unfortunately they
don't have Python, so they are useless here and will cause failed builds if
they pick up the job.

.gitlab-ci.yml

@@ -125,25 +125,25 @@ test:mac_rel:
 win_dbg:
   <<: *build_definition
   script: python ./waf configure build -dT --no-coverage
-  tags: [windows]
+  tags: [windows,msvc,python]
 
 test:win_dbg:
   <<: *test_definition
   script: python ./waf test
   dependencies: [win_dbg]
-  tags: [windows]
+  tags: [windows,msvc,python]
 
 
 win_rel:
   <<: *build_definition
   script: python ./waf configure build -T --no-coverage
-  tags: [windows]
+  tags: [windows,msvc,python]
 
 test:win_rel:
   <<: *test_definition
   script: python ./waf test
   dependencies: [win_rel]
-  tags: [windows]
+  tags: [windows,msvc,python]
 
 
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