Testing requirements not included in `requirements-testing.txt`

[g1rly-c0d3r]

Describe the bug
The requirements-testing.txt file should contain every dependency that is required in order to run the test suite. This is not the case currently.

To Reproduce
Steps to reproduce the behavior:

1. uncomment line 268 in the Dockerfile
2. Build and start specify
3. run docker exec -it specify7 /opt/specify/ve/bin/python3 -m pytest
4. observe the No module named pytest error

pytest has never been included in requirements-testing.txt

Expected behavior
The unit tests should run successfully.

• OS: Ubuntu linux
• Browser: n/a
• Specify 7 Version: main branch
• Database Name: n/a
• Collection name: n/a
• User Name: n/a
• URL: n/a

Reported By
SCC