[Security] Remove unintended payable surface from Mutator.upgrade

src/mutability/Mutator.sol

@@ -45,7 +45,7 @@ contract Mutator is IMutator, Derived, Pausable {
     /// @notice Upgrades the implementation of a proxy and optionally calls its initializer
     /// @param implementation New version of contract to be proxied
     /// @param data Calldata to invoke the instance's initializer
-    function upgrade(IImplementation implementation, bytes memory data) public payable onlyOwner {
+    function upgrade(IImplementation implementation, bytes memory data) public onlyOwner {
         ShortString name = ShortStrings.toShortString(implementation.name());
         if (_nameToMutable[name] == IMutable(address(0))) revert MutatorInvalidMutable();
         _nameToMutable[name].upgrade(implementation, data);

src/mutability/interfaces/IMutator.sol

@@ -13,5 +13,5 @@ interface IMutator is IOwnable, IPausable {
 
     function mutables() external view returns (address[] memory);
     function create(IImplementation implementation, bytes calldata data) external returns (IMutableTransparent newMutable);
-    function upgrade( IImplementation implementation, bytes memory data) external payable;
+    function upgrade( IImplementation implementation, bytes memory data) external;
 }

test/mutability/Mutator.t.sol

@@ -64,6 +64,15 @@ contract MutatorTest is MutableTestV1Deploy {
         mutator.upgrade(impl2, abi.encode(772));
     }
 
+    function test_revertsUpgradeWithValue() public {
+        SampleContractV2 impl2 = new SampleContractV2(201);
+
+        vm.deal(owner, 1);
+        vm.prank(owner);
+        (bool success,) = address(mutator).call{value: 1}(abi.encodeCall(mutator.upgrade, (impl2, abi.encode(773))));
+        assertFalse(success, "upgrade should reject ETH");
+    }
+
     function test_ownerCanPauseAndUnpause() public {
         vm.startPrank(owner);
         vm.expectEmit();