[CSAF] Pattern wrong

[tschmidtb51]

Describe the bug
The pattern generated for the namespace has only a subset of the valid parts as there is a typo in the ABNF.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://certcc.github.io/SSVC/data/abnf/ssvc_namespace_pattern.abnf
2. Look for the privateuse part of BCP47 statement in the ABNF and compare it to the structure given in figure 1 in RFC 5646:
   SSVC: "x" 1*( "-" 2*8ALNUM ) vs RFC 5646: "x" 1*("-" (1*8alphanum))

Expected behavior
SSVC should use "x" 1*( "-" 1*8ALNUM )

Platform details
Include any relevant details like OS, browser, versions, etc.

Additional context
Relevant for CSAF; found in oasis-tcs/csaf#1549 (comment)

Flagging @sei-vsarvepalli for attention

[tschmidtb51]

@bernhardreiter Please submit a PR to fix that. Check whether that can be tested through a namespace test.

[bernhardreiter]

This looks like a defect when the pattern from RFC 5646 was condensed.
And privateuse is there twice in RFC, so two lines are affected.