fix: missing variable declaration

Author: jackie-linz

src/git-version.cr

@@ -126,7 +126,7 @@ module GitVersion
       return {previous_tag, previous_version}
     end
 
-    def get_previous_version: String
+    def get_previous_version : String
       lt, lv = get_previous_tag_and_version
       return lt ? lt : add_prefix_suffix(lv.to_s)
     end

src/main.cr

@@ -10,6 +10,7 @@ release_branch = "master"
 minor_identifier = "feature:"
 major_identifier = "breaking:"
 prefix = ""
+suffix = ""
 log_paths = ""
 
 folder = FileUtils.pwd