PP-8729: Fix github release resource

Github recently changed their release formatting behind the scenes (see concourse/github-release-resource#107). The fix has been pushed for the Concourse github-release-resource, but this is not available in the version of Concourse that BigConcourse is currently running (v7.2.0). Given it may be 'a while' before BigConcourse reaches 7.5.0+, we can instead pin to the version of the resource repo that contains the fix, and specify this as a resource_type.

The naming of the resource type is a bit clumsy but I want it to be clear that this is a version of the resource, not the bleeding edge of the repo. Suggestions for a better name welcome.

ci/pipelines/deploy-smoke-tests.yml

@@ -3,6 +3,13 @@ aws_assumed_role_creds: &aws_assumed_role_creds
   AWS_SECRET_ACCESS_KEY: ((.:role.AWS_SECRET_ACCESS_KEY))
   AWS_SESSION_TOKEN: ((.:role.AWS_SESSION_TOKEN))
 
+resource_types:
+  - name: github-release-1-5-5
+    type: registry-image
+    source:
+      repository: concourse/github-release-resource
+      tag: 1.5.5
+
 resources:
   - name: deploy-smoke-tests-pipeline-definition
     type: git
@@ -27,7 +34,7 @@ resources:
       username: alphagov-pay-ci
       password: ((github-access-token))
   - name: smoke-tests-git-release
-    type: github-release
+    type: github-release-1-5-5
     icon: github
     source:
       owner: alphagov