feat: add tagFormat option to customize Git tag name

lib/git.js

@@ -112,6 +112,17 @@ async function deleteTag(origin, tagName) {
   debug('delete remote tag', shell);
 }
 
+/**
+ * Verify a tag name is a valid Git reference.
+ *
+ * @method verifyTagName
+ * @param {string} tagName the tag name to verify.
+ * @return {boolean} `true` if valid, `false` otherwise.
+ */
+async function verifyTagName(tagName) {
+  return (await execa('git', ['check-ref-format', `refs/tags/${tagName}`], {reject: false})).code === 0;
+}
+
 module.exports = {
   gitTagHead,
   gitTags,
@@ -124,4 +135,5 @@ module.exports = {
   tag,
   push,
   deleteTag,
+  verifyTagName,
 };