Tests do not compile with Clang 10+ because of `-Wxor-used-as-pow` (enabled by default)

[b1ackviking]

FAILED: meta/test/CMakeFiles/test.meta.dir/meta.cpp.o
/usr/bin/clang++  -I/mnt/c/Users/Вова/projects/cpp-project-template/meta/include -std=c++11 -ftemplate-backtrace-limit=0 -Weverything -Werror -pedantic-errors -Wdocumentation -Wno-c++98-compat -Wno-c++98-compat-pedantic -Wno-old-style-cast -Wno-documentation-unknown-command -Wno-missing-prototypes -O2 -g -DNDEBUG -fcolor-diagnostics -MD -MT meta/test/CMakeFiles/test.meta.dir/meta.cpp.o -MF meta/test/CMakeFiles/test.meta.dir/meta.cpp.o.d -o meta/test/CMakeFiles/test.meta.dir/meta.cpp.o -c '/mnt/c/Users/Вова/projects/cpp-project-template/meta/test/meta.cpp'
/mnt/c/Users/Вова/projects/cpp-project-template/meta/test/meta.cpp:1966:45: error: result of '10 ^ 15' is 5; did you mean '1e15'? [-Werror,-Wxor-used-as-pow]
        static_assert(std::is_same<int_<(10 ^ 15)>, bit_xor<int_<10>, int_<15>>>::value, "");
                                         ~~~^~~~
                                         1e15
/mnt/c/Users/Вова/projects/cpp-project-template/meta/test/meta.cpp:1966:45: note: replace expression with '0xA ^ 15' or use 'xor' instead of '^' to silence this warning
/mnt/c/Users/Вова/projects/cpp-project-template/meta/test/meta.cpp:2101:39: error: result of '10 ^ 15' is 5; did you mean '1e15'? [-Werror,-Wxor-used-as-pow]
                std::is_same<int_<(10 ^ 15)>, let<lazy::bit_xor<int_<10>, int_<15>>>>::value, "");
                                   ~~~^~~~
                                   1e15
/mnt/c/Users/Вова/projects/cpp-project-template/meta/test/meta.cpp:2101:39: note: replace expression with '0xA ^ 15' or use 'xor' instead of '^' to silence this warning
2 errors generated.