Update murmurhash3 gem to 0.1.7

What does this MR do and why?

Fixes the error Attention: used pure ruby version of MurmurHash3 on application start up.

For more details see:

• https://github.com/funny-falcon/murmurhash3-ruby/issues/10
• https://github.com/rubygems/rubygems/issues/6205

TLDR is that the latest version of Rubygems 3.4 is more strict about the location of native extension files and refuses to load them from 'incorrect' locations that it used to allow.

We use murmurhash3 as a dependency of unleash-client, a fix has also been posted there. https://github.com/Unleash/unleash-client-ruby/pull/133

How to set up and validate locally

1. On master, run rails console. You will see this on STDERR

   Attention: used pure ruby version of MurmurHash3

2. Check out this branch and run bundle install
3. Run rails console again, you should not see the error.

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