Add old event links to _redirects (#888)

Added old event links to redirect to the events page to avoid 404 errors.

Signed-off-by: Matty Widdop <18513864+MattyTheHacker@users.noreply.github.com>
Co-authored-by: automatic-pr-updater[bot] <217796550+automatic-pr-updater[bot]@users.noreply.github.com>

Author: MattyTheHacker

_redirects

@@ -97,3 +97,12 @@
 
 # Hackathons
 /birminghack https://birminghack.com/
+
+# Old Event Links
+/halloween /events
+/slolan /events
+/bgn /events
+/tnmoc /events
+/scavenger-hunt /events
+/bgn-dietary-form /events
+/escape /events