fix: don't try to fill author info when not needed

fix #126

src/main.ts

@@ -227,7 +227,12 @@ async function checkInputs() {
   // #endregion
 
   // #region author_name, author_email
+  if (getInput('author_name') && getInput('author_email')) {
+    info('> Using author info from inputs...')
+  } else {
+    info('> Some author info is missing, filling from workflow event...')
     let author = event?.head_commit?.author
+
     if (sha && !author) {
       info(
         '> Unable to get commit from workflow event: trying with the GitHub API...'
@@ -252,7 +257,7 @@ async function checkInputs() {
       author = commit?.commit?.author
     }
 
-  if (author) {
+    if (typeof author == 'object') {
       setDefault('author_name', author.name)
       setDefault('author_email', author.email)
     }
@@ -271,6 +276,7 @@ async function checkInputs() {
       setDefault('author_name', 'Add & Commit Action')
       setDefault('author_email', 'actions@github.com')
     }
+  }
 
   info(
     `> Using '${getInput('author_name')} <${getInput(