ruby: add upstream security patches bumping rubygems to 2.6.13

ruby: add upstream security patches bumping rubygems to 2.6.13

We unfortunately cannot use the upstream patches directly as they are not in
'patch -p1' format, so convert them and include instead.

Fixes:

CVE-2017-0899 - RubyGems version 2.6.12 and earlier is vulnerable to
maliciously crafted gem specifications that include terminal escape
characters.  Printing the gem specification would execute terminal escape
sequences.

CVE-2017-0900 - RubyGems version 2.6.12 and earlier is vulnerable to
maliciously crafted gem specifications to cause a denial of service attack
against RubyGems clients who have issued a `query` command.

CVE-2017-0901 - RubyGems version 2.6.12 and earlier fails to validate
specification names, allowing a maliciously crafted gem to potentially
overwrite any file on the filesystem.

CVE-2017-0902 - RubyGems version 2.6.12 and earlier is vulnerable to a DNS
hijacking vulnerability that allows a MITM attacker to force the RubyGems
client to download and install gems from a server that the attacker
controls.

For more details, see
https://www.ruby-lang.org/en/news/2017/08/29/multiple-vulnerabilities-in-rubygems/

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