Bump numpy from 1.17.4 to 1.21.0 in /examples/benchmarks/DoubleEnsemble

Bumps [numpy](https://github.com/numpy/numpy) from 1.17.4 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@v1.17.4...v1.21.0)

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

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

Author: dependabot[bot]

examples/benchmarks/DoubleEnsemble/requirements.txt

@@ -1,3 +1,3 @@
 pandas==1.1.2
-numpy==1.17.4
+numpy==1.21.0
 lightgbm==3.1.0