Update dataset search for sunpy 2.1

[Cadair]

This is work to update our search client for changes upcoming in 2.1. Currently waiting on sunpy/sunpy#4789

[codecov]

Codecov Report

Merging #89 (67fc5ae) into master (0f03e5d) will increase coverage by 0.22%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #89      +/-   ##
==========================================
+ Coverage   91.79%   92.01%   +0.22%     
==========================================
  Files          24       24              
  Lines         963      927      -36     
==========================================
- Hits          884      853      -31     
+ Misses         79       74       -5     

Impacted Files	Coverage Δ
dkist/net/attrs.py	96.55% <ø> (-0.17%)	⬇️
dkist/net/attr_walker.py	98.87% <100.00%> (ø)
dkist/net/client.py	100.00% <100.00%> (+5.05%)	⬆️

---

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 0f03e5d...67fc5ae. Read the comment docs.