Revert "Not requiring on Genoot c:"

This reverts commit edb0778beffebc68c62c128dcf29900360b43857.

The readline.pc for pkg-config has been added to readline in version 8.
Versions below might not find readline with pkg-config.

cli/CMakeLists.txt

@@ -9,7 +9,7 @@ add_executable(ccats-cli src/main.cpp src/iomanager.cpp src/machineiomanager.cpp
 
 # use pkg-config to find readline as it doesnt provide cmake files
 find_package(PkgConfig REQUIRED)
-pkg_check_modules(READLINE readline)
+pkg_check_modules(READLINE REQUIRED readline)
 pkg_check_modules(JSONCPP REQUIRED jsoncpp)
 
 find_package(Threads)