Removing book-clearing bug from gender_frequency

[kenalba]

This PR:

• Removes the bug that clears the last book's text when gender_frequency functions are run on a corpus.

See https://github.com/dhmit/gender_analysis/issues/98 . After discussion, we agreed that the broken lines were probably vestigial and decided to cut them.

[ryaanahmed]

n.b. this is my first pull request! if I am doing something wrong here, please tell me.

Things to fix:

• the title of the PR should be descriptive, so a review can at a glance see what the PR does (so, not "Bug fix" but rather "Fix so-and-so"
• link to the issue that it closes -- in this case #98 (see https://docs.github.com/en/free-pro-team@latest/github/managing-your-work-on-github/linking-a-pull-request-to-an-issue). That'll auto close #98 when this goes in. (And the comment you left over there is probably info for over here.
• request a reviewer (me!) so it shows up in my PRs to review thingie

The commit itself looks good! I'll leave this open just so you can take a whack at fixing the issues in the structure of the PR itself before I merge.

[ryaanahmed]

Better. Please read the docs I linked above and see if you can get this PR to auto close the linked issue.

[kenalba]

... ahem. Yes, sorry, I linked in the body without actually linking. Should be fixed now!

[ryaanahmed]

Looks good!