[Security] Bump django from 2.1.5 to 2.1.7
[Security] Bump django from 2.1.5 to 2.1.7

Bumps [django](https://www.djangoproject.com/) from 2.1.5 to 2.1.7. **This update includes security fixes.**

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
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