Fix running unit tests on Windows

extensions/ql-vscode/package.json

@@ -1188,7 +1188,7 @@
     "watch:extension": "tsc --watch",
     "watch:webpack": "gulp watchView",
     "test": "npm-run-all -p test:*",
-    "test:unit": "LANG=en-US mocha --exit -r ts-node/register -r test/mocha.setup.js test/pure-tests/**/*.ts",
+    "test:unit": "mocha --exit -r ts-node/register -r test/mocha.setup.js test/pure-tests/**/*.ts",
     "test:view": "jest",
     "preintegration": "rm -rf ./out/vscode-tests && gulp",
     "integration": "node ./out/vscode-tests/run-integration-tests.js no-workspace,minimal-workspace",

extensions/ql-vscode/test/mocha.setup.js

@@ -1 +1,2 @@
 process.env.TZ = 'UTC';
+process.env.LANG = 'en-US';