Allow CMake to find the ICU version installed through homebrew

CI/before_install.osx.sh

@@ -13,9 +13,10 @@ brew update --quiet
 command -v ccache >/dev/null 2>&1 || brew install ccache
 command -v cmake >/dev/null 2>&1 || brew install cmake
 command -v qmake >/dev/null 2>&1 || brew install qt@5
-command -v pkgdata >/dev/null 2>&1 || brew install icu4c
+brew install icu4c
 brew install yaml-cpp
 export PATH="/usr/local/opt/qt@5/bin:$PATH"  # needed to use qmake in none default path as qt now points to qt6
+export PKG_CONFIG_PATH="/usr/local/opt/icu4c/lib/pkgconfig"
 
 ccache --version
 cmake --version