Fix install issues in travis (py3.7)

Author: steinitzu

.travis.yml

@@ -12,9 +12,9 @@ env:
   - CELERY=4
   - CELERY=5
 before_install:
+  - pip install --upgrade pip
   - pip install poetry
 install:
   - poetry install -v
-  - if [[ $CELERY == "4" ]]; then travis_retry poetry add celery^4; fi
-  - poetry show
-script: python -m pytest
+  - if [[ $CELERY == "4" ]]; then pip install "celery>=4, <5"; fi
+script: python -m pytest

tests/test_singleton.py

@@ -410,7 +410,7 @@ def simple_task(*args):
             args = [uuid.uuid4(), uuid.uuid4(), uuid.uuid4()]
 
             with pytest.raises(
-                TypeError, match="Object of type UUID is not JSON serializable"
+                TypeError, match=r"Object of type '?UUID'? is not JSON serializable"
             ):
                 [simple_task.apply_async(args=args) for i in range(10)]