🐛 ipset.Check() has problem when version is v7+

[catcher-Rye]

• version

> ipset --version
ipset v7.1, protocol version: 7
Warning: Kernel support protocol versions 6-6 while userspace supports protocol versions 6-7

• this code will return more than version info

out, err := execCommand(ipsetPath, _version).CombinedOutput()

# out is like this
Warning: Kernel support protocol versions 6-6 while userspace supports protocol versions 6-7
ipset v7.1, protocol version: 7

• this code can not get real version

func getMajorVersion(version []byte) int {
	vIndex := bytes.IndexByte(version, 'v')
	dotIndex := bytes.IndexByte(version, '.')
	var majorVersion int
	for i := vIndex + 1; i < dotIndex; i++ {
		if c := version[i]; c >= '0' && c <= '9' {
			majorVersion = majorVersion*10 + int(c-'0')
		} else {
			return 0
		}
	}

	return majorVersion
}

• case error

ipset utility version is not supported, requiring version >= 6.0

this code can replace by regexp