Bump pygments from 2.0.2 to 2.7.4 in /esp

Bumps [pygments](https://github.com/pygments/pygments) from 2.0.2 to 2.7.4.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.0.2...2.7.4)

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

Author: dependabot[bot]

esp/requirements.txt

@@ -26,7 +26,7 @@ pillow==6.2.2 # Required for ImageField, which we use in teacher bios
 psycopg2==2.8.6 # Talks to postgres
 pycurl==7.19.5.1 # Used only in mailing labels and a formstack script which I think is outdated
 pydns==2.3.6 # Used for validating email addresses; imports as "DNS", not "pydns"
-Pygments==2.0.2 # django-extensions dependency
+Pygments==2.7.4 # django-extensions dependency
 pyinotify # Makes dev servers auto-reload
 pylibmc==1.5.0 # Talks to memcached
 pytz==2015.4 # Required for timezone support