bug: fix the false alarm of verification with jwt.WithJSONNumber

[panjf2000]

The current implementation doesn't handle jwt.WithJSONNumber() parse option well, if you set this option and try to parse a JWT, it always fails type conversion here:

gin-jwt/auth_jwt.go

Lines 430 to 433 in 6b68cb3

	if _, ok := claims["exp"].(float64); !ok {
	mw.unauthorized(c, http.StatusBadRequest, mw.HTTPStatusMessageFunc(ErrWrongFormatOfExp, c))
	return
	}

We should also take care of the type json.Number and avoid the false alarm, this is also what https://github.com/golang-jwt/jwt/blob/main/map_claims.go#L40-L56 does.

[panjf2000]

cc @appleboy

[panjf2000]

any comments on this?
@appleboy

[appleboy]

LGTM @panjf2000 Thanks.

[appleboy]

@panjf2000 sorry for the late response.

[panjf2000]

Could you set up a new release for this?