Improve download images logs (#466)

Some of the exception caught by the download images component returned
an empty string since the exception object does not always have a
**string representation** .

Example:

```python
except Exception as e:
    logger.warning(f"Skipping {url}: {e)")
```

returns: 

```bash
Skipping https://2.gravatar.com/avatar/2d7699b189a0d1e40a506aa3b8cad2dc?s=48&d=identicon&r=G: 
```

This makes it difficult to trace back why a url was skipped. Changing to
`repr(e)` seems to fix it since most exeception objects seem to have a
**printable representational string** (at least the httpx ones)

components/download_images/src/main.py

@@ -70,7 +70,7 @@ async def download_image(self, url: str) -> t.Optional[bytes]:
                                             headers={"User-Agent": user_agent_string})
                 image_stream = response.content
             except Exception as e:
-                logger.warning(f"Skipping {url}: {e}")
+                logger.warning(f"Skipping {url}: {repr(e)}")
                 image_stream = None
 
         return image_stream