fix(ci): trigger fastlane on merged main PRs

Run the Linux amd64 fast-lane after a PR is merged to main, while leaving unmerged PRs as no-ops.

Co-authored-by: JustMe <mr.toing@outlook.com>

.woodpecker/main-fastlane.yml

@@ -11,6 +11,8 @@ clone:
 when:
   - event: push
     branch: main
+  - event: pull_request_closed
+    branch: main
 
 concurrency: 1
 
@@ -19,6 +21,7 @@ steps:
     image: bash
     environment:
       NUGET_PACKAGES: /home/justme/.nuget/packages
+      GITEA_BASE: http://127.0.0.1:3100
       ZOT_REGISTRY: registry.oeo.one
       ZOT_USERNAME: justme
       ZOT_SECRET: