Fix sign comparison warning
Fix sign comparison warning

open-eid/chrome-token-signing,metsma/chrome-token-signing,metsma/chrome-token-signing,open-eid/chrome-token-signing,open-eid/chrome-token-signing,metsma/chrome-token-signing,open-eid/chrome-token-signing,metsma/chrome-token-signing,metsma/chrome-token-signing,open-eid/chrome-token-signing