Change private key env name

deploy.sh

@@ -2,4 +2,4 @@
 . ./.env
 forge script script/DCO2s.s.sol:DCO2sScript \
     --fork-url $PROVIDER_URL \
-    --private-key $PK0 --broadcast
+    --private-key $PRIVATE_KEY --broadcast

script/DCO2s.s.sol

@@ -28,7 +28,7 @@ contract DCO2sScript is Script {
     // run is the entry point
     function run() public {
         // startBroadcast and stopBraodcast will let us execute transactions anything between them
-        uint256 deployerPrivateKey = vm.envUint("PK0");
+        uint256 deployerPrivateKey = vm.envUint("PRIVATE_KEY");
         vm.startBroadcast(deployerPrivateKey);
         // here we just need to deploy a new contract
         dco2sc = new DCO2s(defaultAdmin, minter, baseURI, name, symbol);