Update numpy requirement in /python/requirements/CI-tests-conda

Updates the requirements on [numpy](https://github.com/numpy/numpy) to permit the latest version.
- [Release notes](https://github.com/numpy/numpy/releases)
- [Changelog](https://github.com/numpy/numpy/blob/main/doc/HOWTO_RELEASE.rst.txt)
- [Commits](numpy/numpy@v0.2.0...v1.21.2)

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

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

Author: dependabot[bot]

python/requirements/CI-tests-conda/requirements.txt

@@ -1,2 +1,2 @@
-numpy<1.21.2 #Pinned as we get compatibility warnings.
+numpy<1.21.3 #Pinned as we get compatibility warnings.
 msprime==1.0.2