compatibility with latest LC test format

`state.ssz_snappy` file was renamed to `object.ssz_snappy` and
`pyspec_tests` folder was renamed to `BeaconState` as part of
ethereum/consensus-specs#3066

tests/consensus_spec/test_fixture_light_client_single_merkle_proof.nim

@@ -41,7 +41,7 @@ proc runTest(path: string, fork: BeaconStateFork) =
         yaml.load(s, res)
         res
 
-      state = loadForkedState(path/"state.ssz_snappy", fork)
+      state = loadForkedState(path/"object.ssz_snappy", fork)
 
     withState(state[]):
       var computedProof = newSeq[Eth2Digest](log2trunc(proof.leaf_index))
@@ -65,6 +65,6 @@ suite "EF - Light client - Single merkle proof" & preset():
     let
       fork = forkForPathComponent(path).valueOr:
         raiseAssert "Unknown test fork: " & testsPath
-      basePath = testsPath/"pyspec_tests"
+      basePath = testsPath/"BeaconState"
     for kind, path in walkDir(basePath, relative = true, checkDir = true):
       runTest(basePath/path, fork)