GHA: No longer test on push to master

We're monitoring only the pull-requests, so don't waste resources on this

.github/workflows/build-install.yaml

@@ -1,14 +1,6 @@
 name: 'build and installation tests'
 
 on:
-  push:
-    branches: ['master']
-    paths-ignore:
-      - 'AUTHORS'
-      - 'COPYING'
-      - 'NEWS'
-      - 'README.md'
-      - 'doc/**'
   pull_request:
     branches: ['master']
     paths-ignore:

.github/workflows/linters.yaml

@@ -1,11 +1,6 @@
 name: 'linters'
 
 on:
-  push:
-    branches: ['master']
-    paths:
-      - '.github/**'
-      - '**.py'
   pull_request:
     branches: ['master']
     paths:

.github/workflows/tests.yaml

@@ -1,12 +1,6 @@
 name: 'tests'
 
 on:
-  push:
-    branches: ['master']
-    paths:
-      - '.github/**'
-      - '**.py'
-      - 'tests/**'
   pull_request:
     branches: ['master']
     paths: