Bump cryptography from 2.8 to 3.3.2 in /requirements

Bumps [cryptography](https://github.com/pyca/cryptography) from 2.8 to 3.3.2.
- [Release notes](https://github.com/pyca/cryptography/releases)
- [Changelog](https://github.com/pyca/cryptography/blob/main/CHANGELOG.rst)
- [Commits](pyca/cryptography@2.8...3.3.2)

---
updated-dependencies:
- dependency-name: cryptography
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements/tox_requirements27.txt

@@ -1,6 +1,6 @@
 mock==3.0.5
 requests_oauthlib==1.3.0
-cryptography==2.8
+cryptography==3.3.2
 ddt==1.2.2
 django==1.11.29
 django-oauth-toolkit==1.1.3  # not needed in production, unless you need to create provider's Applications

requirements/tox_requirements37.txt

@@ -1,5 +1,5 @@
 requests_oauthlib==1.3.0
-cryptography==2.8
+cryptography==3.3.2
 ddt==1.2.2
 django>=2.2
 django-oauth-toolkit==1.2.0  # not needed in production, unless you need to create provider's Applications