Run dotnet workflows on Ubuntu (#651)

This is in order to avoid dreaded GitHub actions workflow issues on Windows
We still want to run Fable on Windows since there are weird issues that causes Fable to fail for this code on Ubuntu
We also remove old .net versions to hopefully speed up the build

Author: wallymathieu

.github/workflows/dotnetcore.yml

@@ -14,7 +14,7 @@ on:
 jobs:
   build:
 
-    runs-on: windows-latest
+    runs-on: ubuntu-latest
 
     steps:
     - uses: actions/checkout@v2
@@ -23,7 +23,6 @@ jobs:
       with:
         dotnet-version: |
           8.0.x
-          7.0.x
     - name: Restore
       run: git submodule update --init --recursive
     - name: Build with dotnet
@@ -36,7 +35,7 @@ jobs:
       run: dotnet test build.proj -v n
 
   package:
-    runs-on: windows-latest
+    runs-on: ubuntu-latest
     permissions:
       packages: write
       contents: read
@@ -47,7 +46,6 @@ jobs:
       with:
         dotnet-version: |
           8.0.x
-          7.0.x
           6.0.x
     - name: Restore
       run: git submodule update --init --recursive

.github/workflows/fable.yml

@@ -22,7 +22,6 @@ jobs:
       with:
         dotnet-version: |
           8.0.x
-          7.0.x
           6.0.x
     - name: Restore tools
       run: dotnet tool restore

.github/workflows/release-package.yml

@@ -11,7 +11,7 @@ on:
     tags: ['v**']
 jobs:
   package:
-    runs-on: windows-latest
+    runs-on: ubuntu-latest
     permissions:
       packages: write
       contents: read
@@ -22,7 +22,6 @@ jobs:
       with:
         dotnet-version: |
           8.0.x
-          7.0.x
           6.0.x
     - name: Restore
       run: git submodule update --init --recursive

global.json

@@ -6,8 +6,6 @@
   },
 
   "additionalSdks": [
-    "5.0.405",
-    "6.0.201",
-    "7.0.100"
+    "6.0.201"
   ]
 }