Fix typo in release flags

Author: PJK

CMakeLists.txt

@@ -99,7 +99,7 @@ else()
 
   set(CMAKE_C_FLAGS_DEBUG
       "${CMAKE_C_FLAGS_DEBUG} -O0 -pedantic -Wall -Wextra -g -ggdb -DDEBUG=true")
-  set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -O3-pedantic -Wall -Wextra -DNDEBUG")
+  set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -O3 -pedantic -Wall -Wextra -DNDEBUG")
 
   if(SANITIZE)
     set(CMAKE_C_FLAGS_DEBUG