Add Governor module for governance-settable parameters (#2904)

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

contracts/governance/extensions/GovernorProposalThreshold.sol

@@ -8,27 +8,15 @@ import "../Governor.sol";
  * @dev Extension of {Governor} for proposal restriction to token holders with a minimum balance.
  *
  * _Available since v4.3._
+ * _Deprecated since v4.4._
  */
 abstract contract GovernorProposalThreshold is Governor {
-    /**
-     * @dev See {IGovernor-propose}.
-     */
     function propose(
         address[] memory targets,
         uint256[] memory values,
         bytes[] memory calldatas,
         string memory description
     ) public virtual override returns (uint256) {
-        require(
-            getVotes(msg.sender, block.number - 1) >= proposalThreshold(),
-            "GovernorCompatibilityBravo: proposer votes below proposal threshold"
-        );
-
         return super.propose(targets, values, calldatas, description);
     }
-
-    /**
-     * @dev Part of the Governor Bravo's interface: _"The number of votes required in order for a voter to become a proposer"_.
-     */
-    function proposalThreshold() public view virtual returns (uint256);
 }