Update R description version for 2.1.0 release

[jp-dark]

Update the TileDB-SOMA R api version number for the 2.1.0 release.

Closes SOMA-646

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.43%. Comparing base (8af2249) to head (c5a538d).
⚠️ Report is 3 commits behind head on release-2.1.

Additional details and impacted files

@@               Coverage Diff               @@
##           release-2.1    #4292      +/-   ##
===============================================
+ Coverage        76.12%   85.43%   +9.30%     
===============================================
  Files              233       75     -158     
  Lines            32559    13647   -18912     
  Branches          1236        0    -1236     
===============================================
- Hits             24786    11659   -13127     
+ Misses            7349     1988    -5361     
+ Partials           424        0     -424     

Flag	Coverage Δ
libtiledbsoma	?
python	?
r	85.43% <ø> (-0.11%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
python_api	∅ <ø> (∅)
libtiledbsoma	76.58% <ø> (+30.68%)	⬆️

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