Gatekeep check doesn't actually check for house meeting attendance

[Qelxiros]

conditional/conditional/util/member.py

Lines 228 to 231 in 1946a96

	.filter(
	MemberHouseMeetingAttendance.uid == username,
	HouseMeeting.date >= semester_start
	)

These lines need to also filter out Absent/Excused house meetings.

[EgorShternov2]

Hi! I’d like to work on this issue.

I can open a PR with the fix and add a small test (if applicable) to prevent regression.
Please let me know if there are any preferred guidelines for this change.