Bump numpy from 1.19.5 to 1.21.0 in /docker/machine/files

Bumps [numpy](https://github.com/numpy/numpy) from 1.19.5 to 1.21.0.
- [Release notes](https://github.com/numpy/numpy/releases)
- [Changelog](https://github.com/numpy/numpy/blob/main/doc/HOWTO_RELEASE.rst.txt)
- [Commits](numpy/numpy@v1.19.5...v1.21.0)

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

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Author: dependabot[bot]

docker/machine/files/requirements.txt

@@ -2,7 +2,7 @@ scikit-learn==0.22.1
 tqdm==4.32.2
 pymongo==3.8.0
 pandas==1.0.3
-numpy==1.19.5
+numpy==1.21.0
 matplotlib==3.1.0
 mlxtend==0.16.0
 pydot==1.4.1