It is difficult to install modules for use with our debian packages

This issue has been migrated from [#14342](https://github.com/matrix-org/synapse/issues/14342).

---

### Description

I installed pip for mjolnir module and it said nomodule error for mjolnir and i had to move the synapse-antispam files to my mjolnir path and now i am getting this error "ModuleNotFoundError: No module named 'synapse.module_api'"

### Steps to reproduce

- list the steps
- that reproduce the bug
- using hyphens as bullet points
install
pip install -e "git+https://github.com/matrix-org/mjolnir.git#egg=mjolnir&subdirectory=synapse_antispam"

add the conf file to homeserver.yaml
try to restart homeserver and it throws the error nomodulefound

### Homeserver

Another homeserver

### Synapse Version

1.70.1

### Installation Method

Other (please mention below)

### Platform

I followed the instructions on this link https://www.natrius.eu/dokuwiki/doku.php?id=digital:server:matrixsynapse and i am using ubutun 22 lts

### Relevant log output

```shell
File "/opt/venvs/matrix-synapse/lib/python3.10/site-packages/synapse/util/modu>
Nov 01 15:30:06 FansxCliq matrix-synapse[10414]: module = importlib.import_module(module_name)
Nov 01 15:30:06 FansxCliq matrix-synapse[10414]: File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], File "", line 1050, in _gcd_import
File "", line 1027, in _find_and_load
frozen importlib._bootstrap>", line 1004, in _find_and_load_unlocked
matrix-synapse[10414]: ModuleNotFoundError: No module named 'mjolnir'
```

### Anything else that would be useful to know?

_No response_