ci: Adjust base .net version

Directory.Build.props

@@ -97,7 +97,7 @@
 	<!-- BEGIN Uno Specific -->
 
 	<PropertyGroup>
-      <TargetFrameworksOverride>MonoAndroid12.0;xamarinios10;netstandard2.0;xamarinmac20;net6.0-ios;net6.0-macos;net6.0-android;net6.0-maccatalyst</TargetFrameworksOverride>
+      <TargetFrameworksOverride>net7.0;net7.0-ios;net7.0-macos;net7.0-android;net7.0-maccatalyst</TargetFrameworksOverride>
       <_IsUno>true</_IsUno>
       <!--<TargetFrameworksOverride>netstandard2.0</TargetFrameworksOverride>-->
 

global.json

@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "5.0.402",
+    "version": "7.0.302",
     "allowPrerelease": true,
     "rollForward": "latestMajor"
   },