fix version in CHANGES.txt

Author: bdbaddog

CHANGES.txt

@@ -17,7 +17,7 @@ RELEASE  VERSION/DATE TO BE FILLED IN LATER
         - Whatever John Doe did.
 
 
-RELEASE 4.9.0 -  Thu, 27 Mar 2025 11:40:20 -0700
+RELEASE 4.9.1 -  Thu, 27 Mar 2025 11:40:20 -0700
 
   From Mats Wichmann:
     - Fix typos in CCFLAGS test. Didn't affect the test itself, but