configuration: Add missing #include <array>

As user "DaOfficialRolex" on GitHub pointed out:

This is needed to allow for APT on iOS to compile correctly. If not included the two following errors happen while compiling APT.

~/apt/apt-pkg/contrib/configuration.cc:900:44: error: constexpr variable cannot have non-literal type 'const std::array<APT::StringView, 3>'
         constexpr std::array<APT::StringView, 3> magicComments { "clear"_sv, "include"_sv, "x-apt-configure-index"_sv };
                                                  ^
~/apt/apt-pkg/contrib/configuration.cc:900:44: error: implicit instantiation of undefined template 'std::__1::array<APT::StringView, 3>'
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__tuple:219:64: note: template is declared here
template <class _Tp, size_t _Size> struct _LIBCPP_TEMPLATE_VIS array;
                                                               ^

0 files changed, 0 insertions, 0 deletions