Bump reportlab from 3.5.34 to 3.5.55 (#163)

Bumps [reportlab](http://www.reportlab.com/) from 3.5.34 to 3.5.55.

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -24,7 +24,7 @@ ptyprocess==0.5.1
 python-dateutil==2.5.3
 pytz==2016.4
 raven==5.19.0
-reportlab==3.5.34
+reportlab==3.5.55
 requests==2.22.0
 simplegeneric==0.8.1
 traitlets==4.3.3