Bump urllib3 from 1.23 to 1.24.2

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.23 to 1.24.2.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/master/CHANGES.rst)
- [Commits](urllib3/urllib3@1.23...1.24.2)

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

Author: dependabot[bot]

lib.txt

@@ -13,6 +13,6 @@ pytz==2017.2
 requests==2.19.1
 smtplibaio==2.1.1
 split==0.4
-urllib3==1.23
+urllib3==1.24.2
 xlrd==1.1.0
 zope.interface==4.4.3

require.txt

@@ -6,5 +6,5 @@ idna==2.7
 jdcal==1.4
 openpyxl==2.5.8
 requests==2.19.1
-urllib3==1.23
+urllib3==1.24.2
 xlrd==1.1.0