Verifies issue creation for a mismatched `Signature-Input` label.
Issue reported: {
    issue : {
        code : SRIMessageSignatureIssue
        details : {
            sriMessageSignatureIssueDetails : {
                error : SignatureInputHeaderMissingLabel
                integrityAssertions : [
                ]
                request : {
                    requestId : <string>
                    url : http://127.0.0.1:8000/inspector-protocol/resources/sri-message-signature-test.php?signature=signature%3D%3AgHim9e5Pk2H7c9BStOmxSmkyc8%2BioZgoxynu3d4INAT4dwfj5LhvaV9DFnEQ9p7C0hzW4o4Qpkm5aApd6WLLCw%3D%3D%3A&input=not-signature%3D%28%22unencoded-digest%22%3Bsf%29%3Bkeyid%3D%22JrQLj5P%2F89iXES9%2BvFgrIy29clF9CC%2FoPPsw3c5D0bs%3D%22%3Btag%3D%22sri%22
                }
                signatureBase :
            }
        }
    }
}