Fix .gitignore: stop tracking ignored files

backend/lib/openzeppelin-contracts/contracts/mocks/VotesMock.sol

@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "../governance/utils/Votes.sol";
+
+abstract contract VotesMock is Votes {
+    mapping(address => uint256) private _balances;
+    mapping(uint256 => address) private _owners;
+
+    function getTotalSupply() public view returns (uint256) {
+        return _getTotalSupply();
+    }
+
+    function delegate(address account, address newDelegation) public {
+        return _delegate(account, newDelegation);
+    }
+
+    function _getVotingUnits(address account) internal view override returns (uint256) {
+        return _balances[account];
+    }
+
+    function _mint(address account, uint256 voteId) internal {
+        _balances[account] += 1;
+        _owners[voteId] = account;
+        _transferVotingUnits(address(0), account, 1);
+    }
+
+    function _burn(uint256 voteId) internal {
+        address owner = _owners[voteId];
+        _balances[owner] -= 1;
+        _transferVotingUnits(owner, address(0), 1);
+    }
+}
+
+abstract contract VotesTimestampMock is VotesMock {
+    function clock() public view override returns (uint48) {
+        return uint48(block.timestamp);
+    }
+
+    // solhint-disable-next-line func-name-mixedcase
+    function CLOCK_MODE() public view virtual override returns (string memory) {
+        return "mode=timestamp";
+    }
+}