Fix security vulnerability by specifying a secure requests version.

[gkapfham]

No description provided.

[gkapfham]

Hello @Michionlion! I am writing to let you know that GitHub flagged a security problem in GatorGrader because of the fact that the tool is transitively depending on the requests package at a * version. This would mean that we are getting a version that is older than the very recent one that fixed a security vulnerability. However, I am now finding that I can no longer use pipenv on Travis CI with the configurations that we have previously adopted.

There is already an issue about this, but it was closed and I do not understand the comments well enough to see how to re-configure Travis CI. Here is the reference: pypa/pipenv#3247. I should also point out that this might be an active bug for which a fix is in the works, according to pypa/pipenv#3265.

Finally, I'm wondering whether or not this would be an issue for the Gradle plugin and its installation of GatorGrader's dependencies through pipenv? Let me know if you see how to fix the problem or if you think it could become an issue with the Gradle plugin. Thanks! If I hear more on the issue tracker for pipenv, I will follow their advice so as to ensure that this PR passes the build.

[Michionlion]

Everything looks good! I tested this by doing a quick modification of GatorGradle to pull down this branch and install it (using git clone --branch more-secure-pip <url> <folder> instead of the normal command without --branch <name>), and everything worked great. It doesn't look like there are any issues, and if the CI passes now, this PR should be okay to merge!

[gkapfham]

Thanks for merging @Michionlion!