feat: rename polkadot extra to substrate

Co-authored-by: Laurent Peuch <[email protected]>

Author: MHHukiewitz

pyproject.toml

@@ -54,7 +54,7 @@ mqtt = [
 nuls2 = [
     "aleph-nuls2",
 ]
-polkadot = [
+substrate = [
     "py-sr25519-bindings",
     "substrate-interface",
 ]
@@ -112,7 +112,7 @@ features = [
     "dns",
     "ledger",
     "nuls2",
-    "polkadot",
+    "substrate",
     "solana",
     "tezos",
     "encryption",