Testnet semver validation needs better error messages.

[geoknee]

A recent PR triggered a semver validation on OP Sepolia (because of the semver on one contract going backwards) which was misleading.

The backwards semver causes the check to fail and on failure we print a diff against the standard release:

=== FAIL: github.com/ethereum-optimism/superchain-registry/validation TestValidation/OP_Sepolia_Testnet_(11155420)/Standard_Contract_Versions (0.27s)
    superchain-version.go:266: 
                Error Trace:    /home/circleci/project/validation/superchain-version.go:266
                                                        /home/circleci/project/validation/superchain-version.go:41
                                                        /home/circleci/project/validation/validation_test.go:44
                Error:          Should be true
                Test:           TestValidation/OP_Sepolia_Testnet_(11155420)/Standard_Contract_Versions
                Messages:       contract versions do not match the standard versions for the op-contracts/v1.6.0 release 
                                 (-removed from standard / +added to actual):
                                   superchain.ContractVersions{
                                        ... // 5 identical fields
                                        OptimismPortal:  {Version: "3.10.0"},
                                        OptimismPortal2: {},
                                        SystemConfig: superchain.VersionedContract{
                                -               Version: "2.2.0",
                                +               Version: "2.3.0",
                                                ... // 2 ignored fields
                                        },
                                        ProtocolVersions: {},
                                        SuperchainConfig: {},
                                        ... // 2 identical fields
                                        PermissionedDelayedWETH: {},
                                        DisputeGameFactory:      {Version: "1.0.0"},
                                        FaultDisputeGame: superchain.VersionedContract{
                                -               Version: "1.3.0",
                                +               Version: "1.3.1",
                                                ... // 2 ignored fields
                                        },
                                        MIPS: superchain.VersionedContract{
                                -               Version: "1.1.0",
                                +               Version: "1.0.0-beta.7",
                                                ... // 2 ignored fields
                                        },
                                        PermissionedDisputeGame: superchain.VersionedContract{
                                -               Version: "1.3.0",
                                +               Version: "1.3.1",
                                                ... // 2 ignored fields
                                        },
                                        PreimageOracle:         {Version: "1.1.2"},
                                        CannonFaultDisputeGame: {},
                                  }

The error message is not helpful, it claims we are checking strictly against the standard release which we are not. We are checking that each contract semver is equal or greater than standard, and printing the diff if that isn't true. It's also possible that the -beta suffix isn't getting parsed properly, we should add some unit tests for this.