Remove dependencies badge from the README

This badge is useless. We won't update dependencies for the sake of updating them. If a dependency works - i.e. if our unit and integration tests pass with the given dependency, there is no point in updating it to the next minor/major version. The dependencies badge hint at something wrong with the project while it's actually totally expected that dependencies are not updated unless a bug in the depencency is detected that prevents Twing tests to pass.