Update autoprefixer-rails dependency

[ggeverae]

Any chance autoprefixer-rails can be bumped to the latest version?

I believe the error described in #219 is the same as the one described in rails/execjs#99 and should be fixed since autoprefixer-rails version 10.2.5.1: https://github.com/ai/autoprefixer-rails/blob/master/CHANGELOG.md#10251.

Thanks in advance.

[glebm]

We do not have any upper limit on the autoprefixer version, so you can simply update it in your app.

https://github.com/twbs/bootstrap-rubygem/blob/053271759d673f5fe7dea856a2a549d2e8bead1e/bootstrap.gemspec#L18C1-L18C60