Bump interpolation from 2.2.4 to 2.2.6

Bumps [interpolation](https://github.com/EconForge/interpolation.py) from 2.2.4 to 2.2.6.
- [Release notes](https://github.com/EconForge/interpolation.py/releases)
- [Commits](EconForge/interpolation.py@v2.2.4...v2.2.6)

---
updated-dependencies:
- dependency-name: interpolation
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

requirements.txt

@@ -11,5 +11,5 @@ click==8.1.7
 sumo==2.3.8
 h5py==3.11.0
 pyFFTW==0.13.1
-interpolation==2.2.4
+interpolation==2.2.6
 numba==0.58.0