Error with the consolidate post-scan plugin

### Description

ScanCode-toolkit v30.1.0:

```
Extracting archives...
Extracting done.
Setup plugins...
Collect file inventory...
Scan files for: info, licenses, copyrights, packages, emails, urls with 3 process(es)...
/opt/scancodeio/lib/python3.6/site-packages/fingerprints/cleanup.py:54: ICUWarning: Install 'pyicu' for better text transliteration.
text = ascii_text(text)
ERROR: failed to run post-scan plugin: consolidate:
Traceback (most recent call last):
File "/opt/scancodeio/lib/python3.6/site-packages/scancode/cli.py", line 1057, in run_codebase_plugins
plugin.process_codebase(codebase, **kwargs)
File "/opt/scancodeio/lib/python3.6/site-packages/summarycode/plugin_consolidate.py", line 159, in process_codebase
consolidations.extend(get_consolidated_packages(codebase))
File "/opt/scancodeio/lib/python3.6/site-packages/summarycode/plugin_consolidate.py", line 240, in get_consolidated_packages
copyrights=False, holders=True, authors=False, include_years=False):
TypeError: 'Detection' object is not iterable

Scanning done.
Some files failed to scan properly:
ERROR: failed to run post-scan plugin: consolidate:
Traceback (most recent call last):
File "/opt/scancodeio/lib/python3.6/site-packages/scancode/cli.py", line 1057, in run_codebase_plugins
plugin.process_codebase(codebase, **kwargs)
File "/opt/scancodeio/lib/python3.6/site-packages/summarycode/plugin_consolidate.py", line 159, in process_codebase
consolidations.extend(get_consolidated_packages(codebase))
File "/opt/scancodeio/lib/python3.6/site-packages/summarycode/plugin_consolidate.py", line 240, in get_consolidated_packages
copyrights=False, holders=True, authors=False, include_years=False):
TypeError: 'Detection' object is not iterable
Summary: info, licenses, copyrights, packages, emails, urls with 3 process(es)
Errors count: 1
Scan Speed: 41.75 files/sec. 69.18 KB/sec.
Initial counts: 1350 resource(s): 942 file(s) and 408 directorie(s)
Final counts: 1350 resource(s): 942 file(s) and 408 directorie(s) for 1.52 MB
Timings:
scan_start: 2021-10-22T095817.622992
scan_end: 2021-10-22T095843.194147
setup_scan:licenses: 1.33s
setup: 1.33s
inventory: 0.20s
pre-scan:classify: 0.23s
pre-scan: 0.23s
scan: 22.56s
post-scan:consolidate: 0.17s
post-scan:summary: 0.29s
post-scan:license-clarity-score: 0.36s
post-scan: 1.00s
output:json-pp: 0.55s
output: 0.55s
total: 26.17s
Removing temporary files...done.
```

### How To Reproduce

```
--classify --consolidate --copyright --email --info --is-license-text --license --license-clarity-score --license-text --package --summary --summary-key-files --url
```