Bump ecdsa from 0.13 to 0.13.3

Bumps [ecdsa](https://github.com/warner/python-ecdsa) from 0.13 to 0.13.3.
- [Release notes](https://github.com/warner/python-ecdsa/releases)
- [Changelog](https://github.com/warner/python-ecdsa/blob/master/NEWS)
- [Commits](tlsfuzzer/python-ecdsa@python-ecdsa-0.13...python-ecdsa-0.13.3)

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

requirements.txt

@@ -19,7 +19,7 @@ cycler==0.10.0
 Cython==0.29.2
 deap==1.2.2
 decorator==4.3.0
-ecdsa==0.13
+ecdsa==0.13.3
 entrypoints==0.2.3
 funcsigs==1.0.2
 future==0.17.1