replace the ci-trigger action with a external one (#4905)

* use a external action instead

* remove the custom action

* update the action name [skip-ci]

* also update the action name in ci-additional [skip-ci]

* update the last mention of ci-trigger [skip-ci]

Author: keewis

.github/actions/detect-ci-trigger/action.yaml

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v2
         with:
           fetch-depth: 2
-      - uses: ./.github/actions/detect-ci-trigger
+      - uses: xarray-contrib/ci-trigger@v1
         id: detect-trigger
         with:
           keyword: "[skip-ci]"

.github/actions/detect-ci-trigger/script.sh

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v2
         with:
           fetch-depth: 2
-      - uses: ./.github/actions/detect-ci-trigger
+      - uses: xarray-contrib/ci-trigger@v1
         id: detect-trigger
         with:
           keyword: "[skip-ci]"

.github/workflows/ci-additional.yaml

@@ -21,7 +21,7 @@ jobs:
       - uses: actions/checkout@v2
         with:
           fetch-depth: 2
-      - uses: ./.github/actions/detect-ci-trigger
+      - uses: xarray-contrib/ci-trigger@v1
         id: detect-trigger
         with:
           keyword: "[test-upstream]"