Broaden some type signatures

Author: DilumAluthge

src/utilities/new_versions.jl

@@ -303,7 +303,7 @@ end
 
 function force_ci_trigger(
     api::GitLab.GitLabAPI,
-    ci_cfg::CIService,
+    ci_cfg::Union{CIService, Nothing},
     repo::Union{GitLab.Project, Nothing},
     pr_title::AbstractString,
     branch_name::AbstractString,
@@ -316,7 +316,7 @@ end
 
 function force_ci_trigger(
     api::GitHub.GitHubAPI,
-    ci_cfg::CIService,
+    ci_cfg::Union{CIService, Nothing},
     repo::Union{GitHub.Repo, Nothing},
     pr_title::AbstractString,
     branch_name::AbstractString,