Downgrade testcontainers to a 3.8-compatible version

requirements/testing.in

@@ -8,4 +8,4 @@ pytest-mock
 pytest-pretty
 pytest-timeout
 pytz
-testcontainers
+testcontainers<4  # until we remove 3.8 support

requirements/testing.txt

@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile with Python 3.12
+# This file is autogenerated by pip-compile with Python 3.9
 # by the following command:
 #
 #    pip-compile --output-file=requirements/testing.txt --strip-extras requirements/testing.in
@@ -12,10 +12,14 @@ charset-normalizer==3.3.2
     # via requests
 coverage==7.4.4
     # via -r requirements/testing.in
+deprecation==2.1.0
+    # via testcontainers
 dirty-equals==0.7.1.post0
     # via -r requirements/testing.in
 docker==7.1.0
     # via testcontainers
+exceptiongroup==1.2.2
+    # via pytest
 idna==3.7
     # via requests
 iniconfig==2.0.0
@@ -27,7 +31,9 @@ mdurl==0.1.2
 msgpack==1.0.8
     # via -r requirements/testing.in
 packaging==24.0
-    # via pytest
+    # via
+    #   deprecation
+    #   pytest
 pluggy==1.4.0
     # via pytest
 pydantic==2.6.4
@@ -59,17 +65,19 @@ requests==2.32.3
     # via docker
 rich==13.7.1
     # via pytest-pretty
-testcontainers==4.7.2
+testcontainers==3.7.1
     # via -r requirements/testing.in
+tomli==2.0.1
+    # via
+    #   coverage
+    #   pytest
 typing-extensions==4.10.0
     # via
     #   pydantic
     #   pydantic-core
-    #   testcontainers
 urllib3==2.2.2
     # via
     #   docker
     #   requests
-    #   testcontainers
 wrapt==1.16.0
     # via testcontainers

tests/conftest.py

@@ -38,7 +38,7 @@ def test_redis_host(redis_container: RedisContainer) -> str:
 
 @pytest.fixture(scope='session')
 def test_redis_port(redis_container: RedisContainer) -> int:
-    return redis_container.get_exposed_port(redis_container.port)
+    return redis_container.get_exposed_port(redis_container.port_to_expose)
 
 
 @pytest.fixture(scope='session')