fix: add missing dotnet-solution parameter in deploy workflow

.gitea/workflows/deploy.yml

@@ -20,6 +20,7 @@ jobs:
         with:
           dotnet-version: '8.0.x'
           cache: true
+          dotnet-solution: 'backend/JoaoLoureiro.Portfolio.slnx'
 
       - name: Create Backend appsettings.Production.json
         run: |