Update bazel min version to 0.26.0.
Update bazel min version to 0.26.0.

I think this was the first release including the --repo_env arg:
https://github.com/bazelbuild/bazel/commit/d7702b16eb4828b0fe0e92d559fc6de36ee757cc

google/jax,google/jax,tensorflow/probability,google/jax,google/jax,tensorflow/probability