refactor(ci): limit unit-tests run on workflow change to unit-tests itself

Signed-off-by: Sandro-Alessio Gierens <sandro@gierens.de>

.github/workflows/unit-tests.yml

@@ -4,14 +4,14 @@ on:
   push:
     branches: [ main ]
     paths:
-      - '.github/workflows/*'
+      - '.github/workflows/unit-tests.yml'
       - 'src/**'
       - 'Cargo.*'
       - build.rs
   pull_request:
     branches: [ main ]
     paths:
-      - '.github/workflows/*'
+      - '.github/workflows/unit-tests.yml'
       - 'src/**'
       - 'Cargo.*'
       - build.rs