Remove master kernel build workflow

This change removes the master kernel build workflow since it is being
replaced by update workflow which automatically updates the repository
based on the specified tag.

.github/workflows/master.yml

@@ -1,40 +0,0 @@
-name: Kernel Build
-
-on:
-  push:
-    branches: 
-      - master
-      - flavor/*
-
-jobs:
-   build:
-    runs-on: [self-hosted]
-    strategy:
-      matrix:
-        include:
-          - build_type: 'generic'
-            build_cc: gcc-10
-    if: "!contains(github.event.head_commit.message, 'skip ci')"
-    steps:
-    - name: Checkout Sources
-      uses: actions/checkout@v2
-      with:
-          submodules: recursive
-    - name: Build Kernel
-      run: make
-      env:
-          PVE_BUILD_TYPE: ${{ matrix.build_type }}
-          PVE_BUILD_CC: ${{ matrix.build_cc }}
-          PVE_BUILD_CFLAGS: ${{ matrix.build_cflags }}
-    - name: Read Build Information
-      id: read_build_info
-      run: |
-        echo "::set-output name=release::$(sed '1q;d' release.txt)"
-        echo "::set-output name=dst::$(sed '1q;d' artifacts.txt)"
-        echo "::set-output name=hdr::$(sed '2q;d' artifacts.txt)"
-        echo "::set-output name=tools::$(sed '3q;d' artifacts.txt)"
-    - name: Upload Artifacts
-      uses: actions/upload-artifact@v2-preview
-      with:
-        name: debs-${{ matrix.build_type }}
-        path: "*.deb"