Set self-check of azure-pipelines to nonunicode

This is the only schema (to date) which provides an invalid regex
under unicode-mode evaluation. Tweak the metaschema check to agree
with it.

Author: sirosen

.pre-commit-config.yaml

@@ -9,6 +9,11 @@ repos:
     - id: check-metaschema
       name: Validate Vendored Schemas
       files: ^src/check_jsonschema/builtin_schemas/vendor/.*\.json$
+      exclude: ^src/check_jsonschema/builtin_schemas/vendor/azure-pipelines\.json$
+    - id: check-metaschema
+      name: Validate Vendored Schemas (nonunicode regexes)
+      files: ^src/check_jsonschema/builtin_schemas/vendor/azure-pipelines\.json$
+      args: ["--regex-variant", "nonunicode"]
     - id: check-jsonschema
       name: Validate Test Configs
       args: ["--schemafile", "tests/example-files/config_schema.json"]