[qa] Rename python input variable to tx_input

input() is actually the name of a python built in function

test/functional/bumpfee.py

@@ -265,11 +265,11 @@ def test_locked_wallet_fails(rbf_node, dest_address):
 
 
 def spend_one_input(node, dest_address):
-    input = dict(
+    tx_input = dict(
         sequence=BIP125_SEQUENCE_NUMBER, **next(u for u in node.listunspent() if u["amount"] == Decimal("0.00100000")))
     rawtx = node.createrawtransaction(
-        [input], {dest_address: Decimal("0.00050000"),
-                  node.getrawchangeaddress(): Decimal("0.00049000")})
+        [tx_input], {dest_address: Decimal("0.00050000"),
+                     node.getrawchangeaddress(): Decimal("0.00049000")})
     signedtx = node.signrawtransaction(rawtx)
     txid = node.sendrawtransaction(signedtx["hex"])
     return txid