fix: revert change to support hexbytes v1

previous implementation left mostly intact so that in the future if
hexbytes v1 becomes standard, it will be trivial to bump the dependency
without breaking anything.

eth_event/main.py

@@ -299,8 +299,8 @@ def decode_traceTransaction(
 
 
 def _0xstring(value: bytes) -> str:
-    # prepend bytes with 0x to avoid a breaking change from HexBytes v1
-    return f"0x{HexBytes(value).hex()}"
+    # placeholder, will be used to prepend bytes with 0x to avoid HexBytes v1 breaking change
+    return f"{HexBytes(value).hex()}"
 
 
 def _params(abi_params: List) -> List: