Update nightly version format for metapackage

Author: Misha-133

.github/workflows/dotnet.yml

@@ -92,9 +92,15 @@ jobs:
         - name: Is Tag Build
           if: startsWith(github.ref, 'refs/tags/')
           run: echo "IsTagBuild=true" >> $GITHUB_ENV
+          
+        - name: Generate Beta Suffix
+          if: startsWith(github.ref, 'refs/tags/') && contains(github.ref_name, '/')
+          env: 
+            REF_NAME: ${{ github.ref_name }}
+          run: echo "Suffix=${REF_NAME##*/}" >> $GITHUB_ENV
 
         - name: Generate Suffix
-          run: echo "Suffix=$(date +'%Y%m%d')-${{ github.run_number }}" >> $GITHUB_ENV
+          run: echo "Suffix=nightly.$(date +'%Y%m%d').${{ github.run_number }}" >> $GITHUB_ENV
 
         - name: setup NuGet
           uses: nuget/setup-nuget@v2