Outdated `simplejson` dependency

[kpark-hrp]

We are currently pinned on simplejson==3.17.2.

• Doesn't have wheels for Python 3.9 and above.
• Released on July 16, 2020. Making it more than 3 years old.

I think it's time for an upgrade, don't you think? This is keeping us stuck in Python 3.8

[kpark-hrp]

@briensea @alex-pewpew @pushkarchawda @tgsong for visibility

[mahadevan-karthi-dwp]

I vote for this. Need to upgrade simplejson. please if we know whats blocking the upgrade, willing to contribute

[briensea]

Fixed in 2.0.11.