[Docker] Alpine image fix (#9118)

* Revert to alpine3:20 / postgres:16

* Remove old hack

- No longer needed as we are using python 3.11

* Update package requirements for devcontainer

Also fixes some docker warnings from the alpine Dockerfile

* Specify SITE_URL

* Reduce log output during docker image testing

src/backend/InvenTree/InvenTree/settings.py

@@ -47,15 +47,6 @@ if TESTING:
     TEST_RUNNER = 'django_slowtests.testrunner.DiscoverSlowestTestsRunner'
     NUM_SLOW_TESTS = 25
 
-    # Note: The following fix is "required" for docker build workflow
-    # Note: 2022-12-12 still unsure why...
-    if os.getenv('INVENTREE_DOCKER'):
-        # Ensure that sys.path includes global python libs
-        site_packages = '/usr/local/lib/python3.9/site-packages'
-
-        if site_packages not in sys.path:
-            print('Adding missing site-packages path:', site_packages)
-            sys.path.append(site_packages)
 
 # Are environment variables manipulated by tests? Needs to be set by testing code
 TESTING_ENV = False