Fix mutation testing (#63)

Author: vjik

.github/workflows/mutation.yml

@@ -9,6 +9,8 @@ on:
       - 'psalm.xml'
 
   push:
+    branches:
+      - master
     paths-ignore:
       - 'docs/**'
       - 'README.md'
@@ -30,11 +32,8 @@ jobs:
 
     strategy:
       matrix:
-        os:
-          - ubuntu-latest
-
-        php:
-          - 8.1
+        os: ['ubuntu-latest']
+        php: ['8.3']
 
     steps:
       - name: Install service memcached
@@ -70,6 +69,6 @@ jobs:
 
       - name: Run infection
         run: |
-          vendor/bin/roave-infection-static-analysis-plugin -j2 --ignore-msi-with-no-mutations --only-covered
+          vendor/bin/roave-infection-static-analysis-plugin --threads=2 --ignore-msi-with-no-mutations --only-covered
         env:
           STRYKER_DASHBOARD_API_KEY: ${{ secrets.STRYKER_DASHBOARD_API_KEY }}