Remove ecdsa feature of libp2p (#8374)

This compiles, is there any reason to keep `ecdsa`? CC @jxs


Co-Authored-By: Michael Sproul <[email protected]>

Author: michaelsproul

Cargo.lock

@@ -64,7 +64,6 @@ features = [
     "plaintext",
     "secp256k1",
     "macros",
-    "ecdsa",
     "metrics",
     "quic",
     "upnp",