FIX: Correct the .discourse-compatibility syntax (#71)

FIX: Correct the .discourse-compatibility syntax (#71)

Fixes the core build.

diff --git a/.discourse-compatibility b/.discourse-compatibility
index a94d490..27b3b44 100644
--- a/.discourse-compatibility
+++ b/.discourse-compatibility
@@ -1 +1 @@
-2.6.0.beta2 16873e708a3c924549e77f3fea011069358d1511
+2.6.0.beta2: 16873e708a3c924549e77f3fea011069358d1511

GitHub sha: 1085492a

This commit appears in #71 which was approved by udan11 and nbianca. It was merged by CvX.