pw_env_setup: PyPI version bump to 0.0.18

Change-Id: I327231358589bbe820b12f203a9266f5fcbeac41
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/235874
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Reviewed-by: Armando Montanez <amontanez@google.com>
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pw_env_setup/pypi_common_setup.cfg

@@ -13,7 +13,7 @@
 # the License.
 [metadata]
 name = pigweed
-version = 0.0.17
+version = 0.0.18
 author = Pigweed Authors
 author_email = pigweed-developers@googlegroups.com
 description = Pigweed Python modules