Added list_select_related to reduce duplicate SQL queries in admin UI

[phith0n]

Description of the Change

Added list_select_related in the admin IDTokenAdmin to avoid duplicate SQL queries.

Before adding the list_select_related, every 100 IDTokens 206 SQL queries is executed:

After adding the list_select_related, every 100 IDTokens 6 SQL queries is executed:

The total page loading time is 7305 milliseconds and 698 milliseconds respectively in my computer. It expects to reduce 10x the time.

Checklist

• PR only contains one change (considered splitting up PR)
• unit-test added
• documentation updated
• CHANGELOG.md updated (only for user relevant changes)
• author name in AUTHORS

[codecov]

Codecov Report

Merging #1177 (5e8963f) into master (007a5c4) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1177   +/-   ##
=======================================
  Coverage   96.85%   96.85%           
=======================================
  Files          31       31           
  Lines        1812     1813    +1     
=======================================
+ Hits         1755     1756    +1     
  Misses         57       57           

Impacted Files	Coverage Δ
oauth2_provider/admin.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 007a5c4...5e8963f. Read the comment docs.

[n2ygk]

Thanks for this!