Bump pyfxa from 0.7.1 to 0.7.2 (#61)

Bumps [pyfxa](https://github.com/mozilla/PyFxA) from 0.7.1 to 0.7.2.
- [Release notes](https://github.com/mozilla/PyFxA/releases)
- [Changelog](https://github.com/mozilla/PyFxA/blob/master/CHANGES.txt)
- [Commits](mozilla/PyFxA@v0.7.1...v0.7.2)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

Pipfile

@@ -4,7 +4,7 @@ verify_ssl = true
 name = "pypi"
 
 [packages]
-pyfxa = "==0.7.1"
+pyfxa = "==0.7.2"
 
 [dev-packages]
 flake8 = "==3.7.7"