.github/workflows: tune action triggers to run on push/PR

Run on branch pushes or PRs, but ignore tags.

.github/workflows/build-image.yml

@@ -1,6 +1,12 @@
 name: Build and test latest supported Perls
 
-on: [push, pull_request]
+on:
+  push:
+    branches:
+      - '**'
+    tags-ignore:
+      - '*'
+  pull_request:
 
 jobs:
   build-image:

.github/workflows/generate-dockerfiles-patches.yml

@@ -1,6 +1,12 @@
 name: Generate Dockerfiles/patches
 
-on: [push, pull_request]
+on:
+  push:
+    branches:
+      - '**'
+    tags-ignore:
+      - '*'
+  pull_request:
 
 jobs:
   generate: