Fix intermittent test failures due to missing sync_all

test/functional/rpc_psbt.py

@@ -628,6 +628,7 @@ class PSBTTest(BitcoinTestFramework):
 
         self.nodes[0].sendtoaddress(addr, 10)
         self.generate(self.nodes[0], 6)
+        self.sync_all()
         ext_utxo = self.nodes[0].listunspent(addresses=[addr])[0]
 
         # An external input without solving data should result in an error