fix: Remove 20 unregistered students without registration issues

Reconciliation against actual registration issues (pages 1-3) found:
- 67 registration issues in GitHub (matching website count)
- 20 students in roster without registration backing them up
- Removed: DeenadayalanMoodley, Mark-Iott, SarahCranston17, avdhutde,
  blindgeekzone, jekis913, jldail13, kcrpine, mikedoise, nvdaes, nycki96,
  pranav-chinthala, prater-devin, rahul6387, seanmcmahondc-collab,
  soundaryakp1999, taylorarndt, tirupati223, tommym2006, venkateshpotluri

Final count: 66 students (67 - 1 evangelinedionisio already removed)
Matches website registration count.

Author: GitHub Workshop Bot