refactor: clean up unused dependencies and functions

main.go

@@ -4,6 +4,8 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+
+	"git.kjan.de/actions/pull-request-lint/internal/validation"
 )
 
 type GithubEvent struct {
@@ -35,5 +37,10 @@ func main() {
 	}
 
 	prTitle := event.PullRequest.Title
-	fmt.Println("Pull Request Title:", prTitle)
+	semanticValidationErr := validation.ValidateConventionalCommit(prTitle)
+	if semanticValidationErr != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+	os.Exit(0)
 }