Add release workflow

.github/workflows/release.yml

@@ -14,8 +14,8 @@ jobs:
       # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
       - name: Checkout code
         uses: actions/checkout@v2
-		with:
-		  path: source
+		    with:
+          path: source
         
       - name: Install dependencies
         run: |
@@ -24,14 +24,14 @@ jobs:
       - name: Configure
         run: |
           mkdir build
-		  mkdir inst
-		  cd build
-		  cmake ../source -G"Unix Makefiles" -DAMALGAMATE_SOURCES=ON -DCMAKE_INSTALL_PREFIX=../inst
+          mkdir inst
+          cd build
+          cmake ../source -G"Unix Makefiles" -DAMALGAMATE_SOURCES=ON -DCMAKE_INSTALL_PREFIX=../inst
           
       - name: Build
         run: |
           cd build
-		  make install
+          make install
         
       - name: Get current version
         id: relver