fixup rust-secp256k1 v0.30.0 compat

forgot this in schnorr_fun

Author: LLFourn

schnorr_fun/Cargo.toml

@@ -42,7 +42,7 @@ alloc = ["secp256kfun/alloc" ]
 std = ["alloc", "secp256kfun/std"]
 bincode = ["secp256kfun/bincode"]
 serde = ["secp256kfun/serde"]
-libsecp_compat = ["libsecp_compat_0_29", "secp256kfun/libsecp_compat"]
+libsecp_compat = ["libsecp_compat_0_30", "secp256kfun/libsecp_compat"]
 libsecp_compat_0_27 = ["secp256kfun/libsecp_compat_0_27"]
 libsecp_compat_0_28 = ["secp256kfun/libsecp_compat_0_28"]
 libsecp_compat_0_29 = ["secp256kfun/libsecp_compat_0_29"]