test: Correcting test for Table.plot_boxplots to not save the file …

…the test uses to verify the result (#300)

### Summary of Changes

test: Correcting test for `Table.plot_boxplots` to not save the file the
test uses to verify the result

tests/safeds/data/tabular/containers/_table/test_plot_boxplots.py

@@ -23,7 +23,6 @@
 )
 def test_should_match_snapshot(table: Table, path: str) -> None:
     current = table.plot_boxplots()
-    current.to_png_file(resolve_resource_path(path))
     snapshot = Image.from_png_file(resolve_resource_path(path))
 
     # Inlining the expression into the assert causes pytest to hang if the assertion fails when run from PyCharm.