Enable Travis tests for hierarchical_probabilistic_unet

* Fix relative paths in `run.sh` so that it can be invoked from the parent directory
* Ensure that `pip` is up to date
* Don't explicitly `deactivate` - this causes issues since `run.sh` gets executed from within another `virtualenv` created by Travis

PiperOrigin-RevId: 368236037

.travis.yml

@@ -13,6 +13,7 @@ env:
     # - PROJECT="cs_gan"  # TODO(b/184845450): Fix and re-enable
     - PROJECT="gated_linear_networks"
     - PROJECT="geomancer"
+    - PROJECT="hierarchical_probabilistic_unet"
     - PROJECT="iodine"
     - PROJECT="kfac_ferminet_alpha"
     - PROJECT="learning_to_simulate"

hierarchical_probabilistic_unet/run.sh

@@ -13,8 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-python3 -m venv hpu-net-venv
-source hpu-net-venv/bin/activate
-pip3 install .
-python3 model_test.py
-deactivate
+python3 -m venv /tmp/hpu-net-venv
+source /tmp/hpu-net-venv/bin/activate
+pip3 install -U pip
+pip3 install hierarchical_probabilistic_unet/
+python3 hierarchical_probabilistic_unet/model_test.py