[CPFeature-002] Forgot to make the cpVersion static

Author: enuance

Sources/CommitPrefix/CommitMessageHook.swift

@@ -29,9 +29,9 @@ import Foundation
 
 public struct CommitMessageHook {
 
-    private let cpVersionNumber = "1.0.0"
+    private static let cpVersionNumber = "1.0.0"
 
-    private let fileIdentifier = "Created by CommitPrefix \(cpVersionNumber)"
+    private let fileIdentifier = "Created by CommitPrefix \(Self.cpVersionNumber)"
 
     private let hooksDirectory: Folder