Switch macOS and Linux default toolchain to .NET 5.

.github/workflows/ci.yaml

@@ -6,6 +6,29 @@ on:
     branches: [ bleed ]
 
 jobs:
+  linux:
+    name: Linux (.NET 5.0)
+    runs-on: ubuntu-20.04
+
+    steps:
+      - name: Clone Repository
+        uses: actions/checkout@v2
+
+      - name: Install .NET 5
+        uses: actions/setup-dotnet@v1
+        with:
+          dotnet-version: '5.0.x'
+
+      - name: Check Code
+        run: |
+          make check
+
+      - name: Check Mods
+        run: |
+          sudo apt-get install lua5.1
+          make check-scripts
+          make test
+
   linux-mono:
     name: Linux (mono)
     runs-on: ubuntu-20.04
@@ -17,16 +40,15 @@ jobs:
       - name: Check Code
         run: |
           mono --version
-          make check
+          make RUNTIME=mono check
 
       - name: Check Mods
         run: |
-          sudo apt-get install lua5.1
-          make check-scripts
-          make test
+          # check-scripts does not depend on .net/mono, so is not needed here
+          make RUNTIME=mono test
 
   windows:
-    name: Windows (Net 5.0)
+    name: Windows (.NET 5.0)
     runs-on: windows-2019
 
     steps:

.github/workflows/packaging.yml

@@ -15,6 +15,11 @@ jobs:
       - name: Clone Repository
         uses: actions/checkout@v2
 
+      - name: Install .NET 5
+        uses: actions/setup-dotnet@v1
+        with:
+          dotnet-version: '5.0.x'
+
       - name: Prepare Environment
         run: echo "GIT_TAG=${GITHUB_REF#refs/tags/}" >> ${GITHUB_ENV}