Run actions on v3.x branch (#217)

Author: sophiedeziel

.github/workflows/firebase-hosting-merge.yml

@@ -6,6 +6,7 @@ name: Deploy to Firebase Hosting on merge
   push:
     branches:
       - develop
+      - v3.x
 jobs:
   build_and_deploy:
 

.github/workflows/firebase-hosting-pull-request.yml

@@ -5,7 +5,9 @@ name: Deploy to Firebase Hosting on PR
 
 on:
   pull_request:
-    branches: [ develop ]
+    branches:
+      - develop
+      - v3.x
 
 jobs:
   build_and_preview:

.github/workflows/run-tests.yml

@@ -5,9 +5,15 @@ name: Runs All Unit tests
 
 on:
   push:
-    branches: [develop, releases]
+    branches:
+      - develop
+      - releases
+      - v3.x
   pull_request:
-    branches: [develop, releases]
+    branches:
+      - develop
+      - releases
+      - v3.x
 
 jobs:
   build: