CI: migrate to .NET 7 SDK

Author: ForNeVeR

.github/workflows/main.yml

@@ -129,9 +129,7 @@ jobs:
       - name: Set up .NET SDK
         uses: actions/setup-dotnet@v1
         with:
-          dotnet-version: |
-            2.2.x
-            6.0.x
+          dotnet-version: '7.0.x'
       - name: Pack NuGet
         shell: pwsh
         run: dotnet pack -p:PackageVersion=${{ env.PACKAGE_VERSION_BASE }} --output build
@@ -172,9 +170,7 @@ jobs:
       - name: Set up .NET SDK
         uses: actions/setup-dotnet@v1
         with:
-          dotnet-version: |
-            2.2.x
-            6.0.x
+          dotnet-version: '7.0.x'
       - name: Pack NuGet
         shell: pwsh
         run: dotnet pack -p:PackageVersion=${{ env.PACKAGE_VERSION_BASE }} --output build
@@ -229,9 +225,7 @@ jobs:
       - name: Set up .NET SDK
         uses: actions/setup-dotnet@v1
         with:
-          dotnet-version: |
-            2.2.x
-            6.0.x
+          dotnet-version: '7.0.x'
       - name: Pack NuGet
         shell: pwsh
         run: dotnet pack -p:PackageVersion=${{ env.PACKAGE_VERSION_BASE }} --output build
@@ -291,7 +285,7 @@ jobs:
       - name: Set up .NET SDK
         uses: actions/setup-dotnet@v1
         with:
-          dotnet-version: '6.0.x'
+          dotnet-version: '7.0.x'
 
       - name: Read version from ref
         id: version

tdlib.native.proj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.Build.NoTargets/3.4.0">
     <PropertyGroup>
-        <TargetFramework>net6.0</TargetFramework> <!-- this is a dummy value -->
+        <TargetFramework>net7.0</TargetFramework> <!-- this is a dummy value -->
         <NuspecFile>$(MSBuildThisFileDirectory)\tdlib.native.nuspec</NuspecFile>
         <NuspecProperties>version=$(PackageVersion)</NuspecProperties>
     </PropertyGroup>