fix: subject same as from in send_email

src/gleesend/emails.gleam

···
         [
           #("from", json.string(email.from)),
           #("to", json.array(email.to, fn(a) { json.string(a) })),
-          #("subject", json.string(email.string)),
+          #("subject", json.string(email.subject)),
         ],
         case email.bcc {
           Some(bcc) -> [#("bcc", json.array(bcc, fn(a) { json.string(a) }))]

test/gleesend_test.gleam

···
 
 pub fn gleesend_test() {
   let client =
-    resend.Resend(api_key: "// Replace this with your resend api key")
+    gleesend.Resend(api_key: "// Replace this with your resend api key")
 
   create_email(
     client:,