More conservative workflow config

.github/workflows/build.yml

@@ -3,8 +3,6 @@ name: Build
 on:
   pull_request:
   push:
-    branches:
-      - master
 
 jobs:
   test:

.github/workflows/coverage.yml

@@ -2,6 +2,8 @@ name: Test Coverage
 
 on:
   pull_request:
+    branches:
+      - master
   push:
     branches:
       - master

.github/workflows/validate-install.yml

@@ -1,6 +1,10 @@
 on:
   pull_request:
+    branches:
+      - master
   push:
+    branches:
+      - master
 
 name: Validate Install