Cover full extent of data in Band/Range when not given min/max explicitly

[mwaskom]

(
    seaice
    .assign(Year=df["Date"].dt.year)
    .pipe(so.Plot, x="Year", y="Extent")
    .add(so.Band())
    .add(so.Range())
)

Closes #3024

[codecov]

Codecov Report

Merging #3056 (f4d1254) into master (5386adc) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3056   +/-   ##
=======================================
  Coverage   98.37%   98.38%           
=======================================
  Files          72       72           
  Lines       23503    23537   +34     
=======================================
+ Hits        23121    23156   +35     
+ Misses        382      381    -1     

Impacted Files	Coverage Δ
seaborn/_marks/area.py	96.51% <100.00%> (+0.17%)	⬆️
seaborn/_marks/line.py	100.00% <100.00%> (ø)
tests/_marks/test_area.py	100.00% <100.00%> (ø)
tests/_marks/test_line.py	100.00% <100.00%> (ø)
seaborn/_core/scales.py	89.67% <0.00%> (+0.23%)	⬆️