tests: mark two more tests as speconly

Author: fjl

tests/eth_estimateGas/estimate-failed-call.io

@@ -1,3 +1,4 @@
 // estimates a contract call that reverts
+// speconly: client response is only checked for schema validity.
 >> {"jsonrpc":"2.0","id":1,"method":"eth_estimateGas","params":[{"from":"0x0102030000000000000000000000000000000000","input":"0xff030405","to":"0x17e7eedce4ac02ef114a7ed9fe6e2f33feba1667"}]}
 << {"jsonrpc":"2.0","id":1,"error":{"code":3,"message":"execution reverted","data":"0x77726f6e672d63616c6c6461746173697a65"}}

tests/eth_estimateGas/estimate-successful-call.io

@@ -1,5 +1,4 @@
 // estimates a successful contract call
-// 
 // speconly: client response is only checked for schema validity.
 >> {"jsonrpc":"2.0","id":1,"method":"eth_estimateGas","params":[{"from":"0x0102030000000000000000000000000000000000","input":"0xff01","to":"0x17e7eedce4ac02ef114a7ed9fe6e2f33feba1667"}]}
 << {"jsonrpc":"2.0","id":1,"result":"0x5316"}

tests/eth_feeHistory/fee-history.io

@@ -1,3 +1,4 @@
 // gets fee history information
+// speconly: client response is only checked for schema validity.
 >> {"jsonrpc":"2.0","id":1,"method":"eth_feeHistory","params":["0x1","0x1b",[95,99]]}
 << {"jsonrpc":"2.0","id":1,"result":{"oldestBlock":"0x1b","reward":[["0x1","0x1"]],"baseFeePerGas":["0x3b9aca00","0x342dc057"],"gasUsedRatio":[0.0016543629259729885],"baseFeePerBlobGas":["0x0","0x0"],"blobGasUsedRatio":[0]}}