feat: enable discussions in sig-security

[scherersebastian]

Description

Enable discussions to discuss security stuff in sig-security.

Pre-review checks

Please ensure to do as many of the following checks as possible, before asking for committer review:

• [x] DEPENDENCIES are up-to-date. Dash license tool. Committers can open IP issues for restricted libs.
• [x] Copyright and license header are present on all affected files

... no changes to dependencies or files.

[github-actions[bot]]

Diff for a1ae0a6b44fde4770901fe4055cbe385fe98da9b:

```diff Printing local diff for configuration at '/home/runner/work/.eclipsefdn/.eclipsefdn/otterdog-configs/otterdog.json' Actions are indicated with the following symbols: + create ! modify ! forced update - delete Organization eclipse-tractusx[id=eclipse-tractusx] there have been 39 validation infos, enable verbose output with '-v' to to display them. ! repository[name="sig-security"] { ! has_discussions = false -> true ! } Plan: 0 to add, 1 to change, 0 to delete. ``` ```diff Showing diff to a canonical version of the configuration at '/home/runner/work/.eclipsefdn/.eclipsefdn/otterdog-configs/otterdog.json' Organization eclipse-tractusx[id=eclipse-tractusx] ```

[scherersebastian]

FYI @Essenbreis

[Essenbreis]

Great @scherersebastian

[netomi]

discussions have been enabled.