Add flexible voting using latest OZ contracts (#21)

* Removed previous OZ contracts library of 5.0.2

* forge install: openzeppelin-contracts-upgradeable

v5.1.0-rc.0

* Update governor to use GovernorCountingFractional from OZ 5.1 (which requires EVM version 'cancun')

contracts/CompoundGovernor.sol

@@ -5,9 +5,9 @@ import {Initializable} from "@openzeppelin/contracts-upgradeable/proxy/utils/Ini
 import {GovernorUpgradeable} from "@openzeppelin/contracts-upgradeable/governance/GovernorUpgradeable.sol";
 import {GovernorVotesUpgradeable} from
     "@openzeppelin/contracts-upgradeable/governance/extensions/GovernorVotesUpgradeable.sol";
-import {GovernorCountingSimpleUpgradeable} from
-    "@openzeppelin/contracts-upgradeable/governance/extensions/GovernorCountingSimpleUpgradeable.sol";
 import {GovernorSettableFixedQuorumUpgradeable} from "contracts/extensions/GovernorSettableFixedQuorumUpgradeable.sol";
+import {GovernorCountingFractionalUpgradeable} from
+    "@openzeppelin/contracts-upgradeable/governance/extensions/GovernorCountingFractionalUpgradeable.sol";
 import {GovernorTimelockCompoundUpgradeable} from
     "@openzeppelin/contracts-upgradeable/governance/extensions/GovernorTimelockCompoundUpgradeable.sol";
 import {ICompoundTimelock} from "@openzeppelin/contracts/vendor/compound/ICompoundTimelock.sol";
@@ -28,7 +28,7 @@ contract CompoundGovernor is
     GovernorVotesUpgradeable,
     GovernorTimelockCompoundUpgradeable,
     GovernorSettingsUpgradeable,
-    GovernorCountingSimpleUpgradeable,
+    GovernorCountingFractionalUpgradeable,
     GovernorPreventLateQuorumUpgradeable,
     GovernorSettableFixedQuorumUpgradeable,
     OwnableUpgradeable

foundry.toml

@@ -8,7 +8,7 @@
   libs = ['node_modules', 'lib']
   test = 'test'
   cache_path  = 'cache_forge'
-  evm_version = "shanghai"
+  evm_version = "cancun"
   optimizer = true
   optimizer_runs = 200
   solc_version = "0.8.26"

hardhat.config.ts

@@ -15,6 +15,7 @@ const config: HardhatUserConfig = {
             enabled: true,
             runs: 200,
           },
+          evmVersion: "cancun",
         },
       },
       {
@@ -24,6 +25,7 @@ const config: HardhatUserConfig = {
             enabled: true,
             runs: 200,
           },
+          evmVersion: "cancun",
         },
       },
       {
@@ -33,6 +35,7 @@ const config: HardhatUserConfig = {
             enabled: true,
             runs: 200,
           },
+          evmVersion: "cancun",
         },
       },
     ],