Don't use object as base class

[ianthomas23]

Don't use object as base class, it is unnecessary.

[codecov]

Codecov Report

Merging #1286 (d617e59) into main (1c5df74) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1286   +/-   ##
=======================================
  Coverage   85.74%   85.74%           
=======================================
  Files          52       52           
  Lines       10870    10870           
=======================================
  Hits         9320     9320           
  Misses       1550     1550           

Files	Coverage Δ
datashader/bundling.py	98.64% <100.00%> (ø)
datashader/core.py	88.25% <100.00%> (ø)
datashader/datashape/coretypes.py	98.93% <100.00%> (ø)
datashader/datashape/internal_utils.py	97.67% <100.00%> (ø)
datashader/datashape/parser.py	97.93% <100.00%> (ø)
datashader/datashape/type_symbol_table.py	100.00% <100.00%> (ø)
datashader/datashape/typesets.py	98.85% <100.00%> (ø)
datashader/datatypes.py	93.75% <100.00%> (ø)
datashader/glyphs/line.py	93.16% <100.00%> (ø)
datashader/pipeline.py	100.00% <100.00%> (ø)
... and 3 more

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