fix: dependabot directory and remove outdated ignores

Change directory from "/" to "/src" where the .csproj files are.
Remove obsolete MSTest 2.2.2 version ignores.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: lduchosal

.github/dependabot.yml

@@ -1,14 +1,7 @@
 version: 2
 updates:
 - package-ecosystem: nuget
-  directory: "/"
+  directory: "/src"
   schedule:
     interval: daily
   open-pull-requests-limit: 10
-  ignore:
-  - dependency-name: MSTest.TestFramework
-    versions:
-    - 2.2.2
-  - dependency-name: MSTest.TestAdapter
-    versions:
-    - 2.2.2