Update workflows (open-telemetry#227)

.github/workflows/dotnet-format.yml

@@ -1,6 +1,11 @@
 name: dotnet format
 
 on:
+  push:
+    branches: [ main ]
+    paths:
+    - '**.cs'
+    - '.editorconfig'
   pull_request:
     branches: [ main ]
     paths:
@@ -15,10 +20,10 @@ jobs:
     - name: check out code
       uses: actions/checkout@v2
 
-    - name: Setup .NET Core 3.1
+    - name: Setup .NET Core 6.0
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 3.1.x
+        dotnet-version: 6.0.x
 
     - name: Install format tool
       run: dotnet tool install -g dotnet-format

.github/workflows/markdownlint.yml

@@ -1,6 +1,10 @@
 name: markdownlint
 
 on:
+  push:
+    branches: [ main ]
+    paths:
+    - '**.md'
   pull_request:
     branches: [ main ]
     paths:

.github/workflows/sanitycheck.yml

@@ -1,6 +1,8 @@
 name: sanitycheck
 
 on:
+  push:
+    branches: [ main ]
   pull_request:
     branches: [ main ]