fix(tempo): forward feePayer: false in transaction request formatter (#4525)

Amp-Thread-ID: https://ampcode.com/threads/T-019d98fb-3b6f-767b-9555-3db4d1395a4a

Author: jxom

.changeset/forward-feepayer-false.md

@@ -0,0 +1,5 @@
+---
+'viem': patch
+---
+
+Fixed Tempo formatter to forward `feePayer: false` in transaction requests.

src/tempo/Formatters.ts

@@ -133,7 +133,7 @@ export function formatTransactionRequest(
     ...(keyData ? { keyData } : {}),
     ...(keyId ? { keyId } : {}),
     ...(keyType ? { keyType } : {}),
-    ...(request.feePayer
+    ...(typeof request.feePayer !== 'undefined'
       ? {
           feePayer:
             typeof request.feePayer === 'object'