Don't REQUIRED in find_dependency.

`find_dependency` exists to wire up the `REQUIRED`-ness from callers. That is, `find_package(coinbase-advanced-cpp QUIET)` needs to `QUIET`-ly return "not available" if `nlohmann_json` is missing, but adding the `REQUIRED` here makes that fail.

For more information, see https://cmake.org/cmake/help/latest/module/CMakeFindDependencyMacro.html

Drive-by: Fix the version number of slick-net to match.

GPT 5.4 discovered the version number mismatch problem in microsoft/vcpkg#52259 but it did neither wrote this message nor made this change.

Author: BillyONeal

cmake/coinbase-advanced-cppConfig.cmake.in

@@ -2,10 +2,10 @@
 
 include(CMakeFindDependencyMacro)
 
-find_dependency(nlohmann_json CONFIG REQUIRED)
-find_dependency(OpenSSL CONFIG REQUIRED)
-find_dependency(jwt-cpp CONFIG REQUIRED)
-find_dependency(slick-net 1.2.4 CONFIG QUIET)
+find_dependency(nlohmann_json CONFIG)
+find_dependency(OpenSSL CONFIG)
+find_dependency(jwt-cpp CONFIG)
+find_dependency(slick-net 2.1.0 CONFIG)
 
 if(NOT slick-net_FOUND)
     message(STATUS "Fetching slick-net...")
@@ -15,7 +15,7 @@ if(NOT slick-net_FOUND)
     FetchContent_Declare(
         slick-net
         GIT_REPOSITORY https://github.com/SlickQuant/slick-net.git
-        GIT_TAG v1.2.4
+        GIT_TAG v2.1.0
     )
     FetchContent_MakeAvailable(slick-net)
 endif()