Bump tarantool-python submodule (remove test-run)

This change removes the test-run submodule from `lib/tarantool-python`.

The idea is to get rid of this 'recursive' nesting of test-run and
tarantool-python submodules into each other. Those nested submodules
contain old resivions of the code. It confuses linters, which looking
for code recursively (such as luacheck). See [1] for details.

After this commit we can eliminate the `test-run/**/*.lua` exclusion
from `.luacheckrc` in tarantool.

As the side effect, `git clone --recursive <...>` will be faster.

[1]: tarantool/tarantool-python#189

Follows up PR #266