Silence CMake warning from exteral cmake project (pcre2)

The warning reads:

CMake Deprecation Warning at CMakeLists.txt:101 (CMAKE_MINIMUM_REQUIRED):
Compatibility with CMake < 2.8.12 will be removed from a future version of
CMake.

cmake/pcre.cmake

@@ -48,6 +48,7 @@ MACRO(BUNDLE_PCRE2)
     URL_MD5  8c1699a725d4b28410adf4b964ebbcb7
     INSTALL_COMMAND ""
     CMAKE_ARGS
+      "-DCMAKE_WARN_DEPRECATED=FALSE"
       "-DPCRE2_BUILD_TESTS=OFF"
       "-DPCRE2_BUILD_PCRE2GREP=OFF"
       "-DBUILD_SHARED_LIBS=OFF"