chore: fixes deployment to run with shared runners

.gitlab-ci.yml

@@ -3,12 +3,16 @@ stages:
   - publish
 
 running tests for tag:
+  tags:
+    - shared
   image: mcr.microsoft.com/dotnet/core/sdk:3.1
   stage: test
   script:
     - dotnet test ./tests
 
 publish to nuget:
+  tags:
+    - shared
   only:
     - /^\d*.\d*.\d*$/ # gets triggered if the commit tag is in the form n.n.n where n is any number
   image: mcr.microsoft.com/dotnet/core/sdk:3.1