[ci] Make run name dynamic with c++ standard mark

Author: halx99

.github/workflows/build.yml renamed to .github/workflows/ci.yml

@@ -1,4 +1,4 @@
-name: build
+name: ci
 
 on:
   push:
@@ -28,6 +28,8 @@ on:
 env:
   __1K_CXXSTD: '${{ inputs.cxxstd }}'
 
+run-name: 'ci@c++${{ inputs.cxxstd || 20 }}'
+
 jobs:
   win32:
     runs-on: windows-latest