Revert "fix: Bump redis-plus-plus to v1.3.14"

This reverts commit 6cab790.

Author: keelerm84

cmake/redis-plus-plus.cmake

@@ -18,9 +18,11 @@ include_directories(${CMAKE_CURRENT_BINARY_DIR}/_deps)
 
 set(REDIS_PLUS_PLUS_BUILD_TEST OFF CACHE BOOL "" FORCE)
 
+# 1.3.7 is the last release that works with FetchContent, due to a problem with CheckSymbolExists
+# when it tries to do feature detection on hiredis.
 FetchContent_Declare(redis-plus-plus
         GIT_REPOSITORY https://github.com/sewenew/redis-plus-plus.git
-        GIT_TAG 1.3.14
+        GIT_TAG 1.3.7
         GIT_SHALLOW TRUE
 )