fix: fix pull request url format mismatch (#1927)

#1924

Author: catchyzheng

internal/librarian/tag_and_release.go

@@ -32,7 +32,7 @@ import (
 )
 
 const (
-	pullRequestSegments  = 5
+	pullRequestSegments  = 7
 	tagAndReleaseCmdName = "tag-and-release"
 	releasePendingLabel  = "release:pending"
 	releaseDoneLabel     = "release:done"

internal/librarian/tag_and_release_test.go

@@ -76,7 +76,7 @@ func TestDeterminePullRequestsToProcess(t *testing.T) {
 		{
 			name: "with pull request config",
 			cfg: &config.Config{
-				PullRequest: "github.com/googleapis/librarian/pulls/123",
+				PullRequest: "https://github.com/googleapis/librarian/pulls/123",
 			},
 			ghClient: &mockGitHubClient{
 				getPullRequestCalls: 1,
@@ -95,15 +95,15 @@ func TestDeterminePullRequestsToProcess(t *testing.T) {
 		{
 			name: "invalid pull request number",
 			cfg: &config.Config{
-				PullRequest: "github.com/googleapis/librarian/pulls/abc",
+				PullRequest: "https://github.com/googleapis/librarian/pulls/abc",
 			},
 			ghClient:   &mockGitHubClient{},
 			wantErrMsg: "invalid pull request number",
 		},
 		{
 			name: "get pull request error",
 			cfg: &config.Config{
-				PullRequest: "github.com/googleapis/librarian/pulls/123",
+				PullRequest: "https://github.com/googleapis/librarian/pulls/123",
 			},
 			ghClient: &mockGitHubClient{
 				getPullRequestCalls: 1,