Bump numpy from 1.19.2 to 1.20.3 (#740)

Bumps [numpy](https://github.com/numpy/numpy) from 1.19.2 to 1.20.3.
- [Release notes](https://github.com/numpy/numpy/releases)
- [Changelog](https://github.com/numpy/numpy/blob/main/doc/HOWTO_RELEASE.rst.txt)
- [Commits](numpy/numpy@v1.19.2...v1.20.3)

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

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

Author: dependabot[bot]

requirements_dev_numpy.txt

@@ -1,4 +1,4 @@
 # Break this out into a separate file to allow testing against
 # different versions of numpy. This file should pin to the latest
 # numpy version.
-numpy==1.19.2; python_version >= '3.6'
+numpy==1.20.3; python_version >= '3.6'