package/ruby: security bump to version 2.4.6

package/ruby: security bump to version 2.4.6

Fixes the following security issues:

- CVE-2019-8320: Delete directory using symlink when decompressing tar
- CVE-2019-8321: Escape sequence injection vulnerability in verbose
- CVE-2019-8322: Escape sequence injection vulnerability in gem owner
- CVE-2019-8323: Escape sequence injection vulnerability in API response handling
- CVE-2019-8324: Installing a malicious gem may lead to arbitrary code execution
- CVE-2019-8325: Escape sequence injection vulnerability in errors

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>