Fix tests to support mlflow v2.7 (nv-morpheus#1220)

Closes nv-morpheus#1199

## By Submitting this PR I confirm:
- I am familiar with the [Contributing Guidelines](https://github.com/nv-morpheus/Morpheus/blob/main/docs/source/developer_guide/contributing.md).
- When the PR is ready for review, new or existing tests cover these changes.
- When the PR is ready for review, the documentation is up to date with these changes.

Authors:
  - David Gardner (https://github.com/dagardner-nv)

Approvers:
  - Michael Demoret (https://github.com/mdemoret-nv)

URL: nv-morpheus#1220

docker/conda/environments/cuda11.8_dev.yml

@@ -65,7 +65,7 @@ dependencies:
     - jupyterlab
     - libgrpc>=1.49
     - librdkafka=1.9.2
-    - mlflow>=2.2.1,<2.7
+    - mlflow>=2.2.1,<3
     - mrc=23.11
     - networkx=3.1
     - ninja=1.10

tests/examples/digital_fingerprinting/test_dfp_mlflow_model_writer.py

@@ -18,6 +18,8 @@
 from collections import namedtuple
 from unittest import mock
 
+# This import is needed to ensure our mocks work correctly, otherwise mlflow.pytorch is a stub.
+import mlflow.pytorch  # noqa: F401 pylint: disable=unused-import
 import pandas as pd
 import pytest