Bump cryptography from 2.8 to 3.2 in /IRIS_data_download

Bumps [cryptography](https://github.com/pyca/cryptography) from 2.8 to 3.2.
- [Release notes](https://github.com/pyca/cryptography/releases)
- [Changelog](https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst)
- [Commits](pyca/cryptography@2.8...3.2)

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

Author: dependabot[bot]

IRIS_data_download/requirements.txt

@@ -1,7 +1,7 @@
 certifi==2019.9.11
 cffi==1.13.2
 chardet==3.0.4
-cryptography==2.8
+cryptography==3.2
 cycler==0.10.0
 decorator==4.4.1
 future==0.18.2