Increase JS tests timeout

Author: shepeliev

firebase-firestore/karma.config.d/karma.conf.js

@@ -0,0 +1,8 @@
+// Some tests are fluky in GitHub Actions, so we increase the timeout.
+config.set({
+    client: {
+      mocha: {
+        timeout: 5000
+      }
+    },
+});