CI: some version updates

Since we have a periodic builds now, we could start using more volatile
versions of certain CI dependencies.

Author: ForNeVeR

.github/workflows/main.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ${{ matrix.image }}
     strategy:
       matrix:
-        image: [macos-10.15, ubuntu-18.04, windows-2019]
+        image: [macos-10.15, ubuntu-20.04, windows-2019]
     env:
       DOTNET_SKIP_FIRST_TIME_EXPERIENCE: 1
       DOTNET_CLI_TELEMETRY_OPTOUT: 1
@@ -25,7 +25,7 @@ jobs:
 
       # Frontend
       - name: NPM Cache
-        uses: actions/cache@v1.1.0
+        uses: actions/cache@v1
         with:
           path: ${{ env.NPM_CACHE }}
           key: ${{ runner.os }}.npm.${{ hashFiles('**/npm-shrinkwrap.json') }}
@@ -38,11 +38,11 @@ jobs:
 
       # Backend
       - name: Setup .NET Core SDK
-        uses: actions/setup-dotnet@v1.7.2
+        uses: actions/setup-dotnet@v1
         with:
-          dotnet-version: '3.1.201'
+          dotnet-version: '3.1.x'
       - name: NuGet Cache
-        uses: actions/cache@v1.1.0
+        uses: actions/cache@v2
         with:
           path: ${{ env.NUGET_PACKAGES }}
           key: ${{ runner.os }}.nuget.${{ hashFiles('**/*.fsproj') }}