Refactor: Stats card: Set username param type for totalCommitsFetcher…

… function inside data fetcher (anuraghazra#3068)

src/fetchers/stats-fetcher.js

@@ -143,7 +143,7 @@ const statsFetcher = async (username) => {
 /**
  * Fetch all the commits for all the repositories of a given username.
  *
- * @param {*} username GitHub username.
+ * @param {string} username GitHub username.
  * @returns {Promise<number>} Total commits.
  *
  * @description Done like this because the GitHub API does not provide a way to fetch all the commits. See