Update workflow environment

Author: babenkoivan

.github/workflows/code-style.yml

@@ -4,7 +4,7 @@ on: [push, pull_request]
 
 jobs:
   style-check:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout code
         uses: actions/checkout@v2

.github/workflows/static-analysis.yml

@@ -4,7 +4,7 @@ on: [push, pull_request]
 
 jobs:
   static-analysis:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout code
         uses: actions/checkout@v2

.github/workflows/test.yml

@@ -4,7 +4,7 @@ on: [push, pull_request]
 
 jobs:
   test:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     strategy:
       matrix:
         php: [7.4, 8.0, 8.1]