Changed hardfork from istanbul to cancun

Author: Alexvozhak

README.md

@@ -118,7 +118,7 @@ module.exports = {
     hardhat: {
       chainId: 17000,
       blockGasLimit: 92000000,
-      hardfork: "istanbul",
+      hardfork: "cancun",
     }
   },
 };

hardhat_configs/holesky_hardhat_config.js

@@ -4,7 +4,7 @@ module.exports = {
     hardhat: {
       chainId: 17000,
       blockGasLimit: 92000000,
-      hardfork: "istanbul",
+      hardfork: "cancun",
     }
   },
 };

hardhat_configs/sepolia_hardhat_config.js

@@ -4,7 +4,7 @@ module.exports = {
     hardhat: {
       chainId: 11155111,
       blockGasLimit: 92000000,
-      hardfork: "istanbul",
+      hardfork: "cancun",
     }
   },
 };