Wrong formatting of MaxAllowedMolecules accepted in config file
**Describe the bug**
String is not formatted when Exception is thrown.

**To Reproduce**
Put 50 input molecules at once in the configuration file:
molecules = ['mol1.pdb', ..., 'mol50.pdb']

```
raise ConfigurationError("Too many molecules defined, max is {max_molecules_allowed}.")
```

**Expected behavior**
Should return the value of max_molecules_allowed instead of the variable name

**Additional context (optional - remove if not relevant)**
I will solve this soon, this is just to keep track


diff --git a/src/haddock/gear/prepare_run.py b/src/haddock/gear/prepare_run.py
index 64535bbc..5a4f5e87 100644
--- a/src/haddock/gear/prepare_run.py
+++ b/src/haddock/gear/prepare_run.py
@@ -259,7 +259,7 @@ def setup_run(
             )
 
         if len(modules_params["topoaa.1"]["molecules"]) > max_molecules_allowed:
-            raise ConfigurationError("Too many molecules defined, max is {max_molecules_allowed}.")  # noqa: E501
+            raise ConfigurationError(f"Too many molecules defined, max is {max_molecules_allowed}.")  # noqa: E501
 
         zero_fill.read(modules_params)
 
['src/haddock/gear/prepare_run.py']