[+] add concurrency clause to GHA workflows

Author: pashagolub

.github/workflows/build.yml

@@ -2,6 +2,10 @@ name: Build & Test
 on:
   workflow_dispatch:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
 
   test-docker-images:

.github/workflows/docker.yml

@@ -11,6 +11,10 @@ on:
       - 'master'
   workflow_dispatch:
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   docker:
     if: true # false to skip job during debug