Update gem rack (3.2.5->3.2.6) (#2761)

MANY vulnerability reports. There's no point in analyzing them,
we're just going *immediately* update. Rack is directly
exposed to the Internet, so we *definitely* care about any
vulnerabilities in rack.

Signed-off-by: David A. Wheeler <[email protected]>

Author: david-a-wheeler

Gemfile.lock

@@ -387,7 +387,7 @@ GEM
       nio4r (~> 2.0)
     raabro (1.4.0)
     racc (1.8.1)
-    rack (3.2.5)
+    rack (3.2.6)
     rack-attack (6.8.0)
       rack (>= 1.0, < 4)
     rack-cors (3.0.0)