build: update karma to v6.3.8 which contains sourcemap generated-code fix (#23922)

Updates to Karma v6.3.8 which contains a sourcemap fix we landed
upstream. Previous versions of Karma printed/polluted the log output
when an error is thrown due to generated-code being part of stack
traces (due to ESBuild downleveling).

More details here:
https://gist.github.com/devversion/549d25915c2dc98a8896ba4408a1e27c.

karma-runner/karma@4f23b14

Author: devversion

package.json

@@ -179,15 +179,15 @@
     "jasmine-core": "^3.6.0",
     "jsonc-parser": "^3.0.0",
     "kagekiri": "^1.4.1",
-    "karma": "^4.4.1",
+    "karma": "^6.3.8",
     "karma-browserstack-launcher": "^1.6.0",
     "karma-chrome-launcher": "^3.1.0",
-    "karma-firefox-launcher": "^2.0.0",
+    "karma-firefox-launcher": "^2.1.2",
     "karma-jasmine": "^4.0.1",
-    "karma-parallel": "^0.3.0",
+    "karma-parallel": "^0.3.1",
     "karma-requirejs": "^1.1.0",
     "karma-sauce-launcher": "^4.3.6",
-    "karma-sourcemap-loader": "^0.3.7",
+    "karma-sourcemap-loader": "^0.3.8",
     "luxon": "^2.0.0",
     "madge": "^4.0.0",
     "marked": "^2.0.0",