fossa: update the check to skip running in forks (#486)

This is a check that was done in many repos with "github.repository == 'open-telemetry/opentelemetry.io'", using the fork value is more a more generic way to achieve the same

Signed-off-by: Alex Boten <223565+codeboten@users.noreply.github.com>

Author: codeboten

.github/workflows/fossa.yml

@@ -15,7 +15,7 @@ permissions: {}
 jobs:
   fossa:
     name: FOSSA scanning
-    if: github.repository_owner == 'open-telemetry'
+    if: ${{ github.repository_owner == 'open-telemetry' && github.event.repository.fork == false }}
     runs-on: ubuntu-slim
     permissions:
       contents: read # for actions/checkout