Drop support for dotnet3.1 (EOL) (#83)

Author: dgrove-oss

.github/workflows/ci.yaml

@@ -88,8 +88,6 @@ jobs:
         working-directory: runtime
         run: |
           SHORT_COMMIT=$(git rev-parse --short "$GITHUB_SHA")
-          ./gradlew :core:dotnet3.1:distDocker -PdockerRegistry=docker.io -PdockerImagePrefix=openwhisk -PdockerImageTag=nightly
-          ./gradlew :core:dotnet3.1:distDocker -PdockerRegistry=docker.io -PdockerImagePrefix=openwhisk -PdockerImageTag=$SHORT_COMMIT
           ./gradlew :core:net6.0:distDocker -PdockerRegistry=docker.io -PdockerImagePrefix=openwhisk -PdockerImageTag=nightly
           ./gradlew :core:net6.0:distDocker -PdockerRegistry=docker.io -PdockerImagePrefix=openwhisk -PdockerImageTag=$SHORT_COMMIT
       - name: Push Release Images
@@ -98,9 +96,7 @@ jobs:
         run: |
           RUNTIME_VERSION=${GITHUB_REF_NAME%@*}
           IMAGE_TAG=${GITHUB_REF_NAME##*@}
-          if [ ${RUNTIME_VERSION} == "3.1" ]; then
-            RUNTIME="dotnet3.1"
-          elif [ ${RUNTIME_VERSION} == "6.0" ]; then
+          if [ ${RUNTIME_VERSION} == "6.0" ]; then
             RUNTIME="net6.0"
           fi
           ./gradlew :core:$RUNTIME:distDocker -PdockerRegistry=docker.io -PdockerImagePrefix=openwhisk -PdockerImageTag=$IMAGE_TAG

README.md

@@ -124,12 +124,10 @@ namespace Apache.OpenWhisk.Tests.Dotnet
 
 ## Changelogs
 
-- [.NET Core 3.1 CHANGELOG.md](core/dotnet3.1/CHANGELOG.md)
 - [.NET 6.0 CHANGELOG.md](core/net6.0/CHANGELOG.md)
 
 ## Quick Start Guides
 
-- [.NET Core 3.1](core/dotnet3.1/QUICKSTART.md)
 - [.NET Core 6.0](core/net6.0/QUICKSTART.md)
 
 # License