Add pull requests to github workflows

Author: calc84maniac

.github/workflows/cmake-windows.yml

@@ -3,6 +3,8 @@ name: "CMake Windows"
 on:
   push:
     branches: [z80]
+  pull_request:
+    branches: [z80]
 
 jobs:
   build-llvm:
@@ -174,7 +176,7 @@ jobs:
   nightly:
     runs-on: ubuntu-latest
     needs: [build-clang]
-    if: github.ref == 'refs/heads/z80'
+    if: github.ref == 'refs/heads/z80' && github.event_name != 'pull_request'
 
     steps:
       - name: Download Windows ez80-clang

.github/workflows/cmake.yml

@@ -3,6 +3,8 @@ name: "CMake Linux/macOS"
 on:
   push:
     branches: [z80]
+  pull_request:
+    branches: [z80]
 
 jobs:
   build-llvm:
@@ -362,7 +364,7 @@ jobs:
   nightly:
     runs-on: ubuntu-latest
     needs: [build-clang, test-llvm-z80]
-    if: github.ref == 'refs/heads/z80'
+    if: github.ref == 'refs/heads/z80' && github.event_name != 'pull_request'
 
     steps:
       - name: Download Ubuntu 22.04 ez80-clang