test: unable to build keepkey emulator on Ubuntu 21.10

[Sjors]

./setup_environment.sh --keepkey
...
Scanning dependencies of target rle-dump
[ 86%] Building CXX object tools/rle-dump/CMakeFiles/rle-dump.dir/main.cpp.o
[ 86%] Linking CXX executable ../../bin/rle-dump
[ 86%] Built target rle-dump
Scanning dependencies of target gtest
[ 87%] Building CXX object deps/googletest/googlemock/gtest/CMakeFiles/gtest.dir/src/gtest-all.cc.o
In file included from /home/dev/HWI/test/work/keepkey-firmware/deps/googletest/googletest/src/gtest-all.cc:43:
/home/dev/HWI/test/work/keepkey-firmware/deps/googletest/googletest/src/gtest-death-test.cc: In function ‘bool testing::internal::StackGrowsDown()’:
/home/dev/HWI/test/work/keepkey-firmware/deps/googletest/googletest/src/gtest-death-test.cc:1012:24: error: ‘dummy’ may be used uninitialized [-Werror=maybe-uninitialized]
 1012 |   StackLowerThanAddress(&dummy, &result);
      |   ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
/home/dev/HWI/test/work/keepkey-firmware/deps/googletest/googletest/src/gtest-death-test.cc:1002:13: note: by argument 1 of type ‘const void*’ to ‘void testing::internal::StackLowerThanAddress(const void*, bool*)’ declared here
 1002 | static void StackLowerThanAddress(const void* ptr, bool* result) {
      |             ^~~~~~~~~~~~~~~~~~~~~
/home/dev/HWI/test/work/keepkey-firmware/deps/googletest/googletest/src/gtest-death-test.cc:1010:7: note: ‘dummy’ declared here
 1010 |   int dummy;
      |       ^~~~~
cc1plus: all warnings being treated as errors
make[2]: *** [deps/googletest/googlemock/gtest/CMakeFiles/gtest.dir/build.make:82: deps/googletest/googlemock/gtest/CMakeFiles/gtest.dir/src/gtest-all.cc.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:1232: deps/googletest/googlemock/gtest/CMakeFiles/gtest.dir/all] Error 2
make: *** [Makefile:160: all] Error 2

[Sjors]

I guess suppressing -Werror=maybe-uninitialize would do the trick? (it's not our job to test the firmware/emulator itself)