The tolerance on these was increased in various PRs, with notes to
reduce/remove them, so they were removed in matplotlib#30184, but should have been
reverted to a smaller value.

- `test_floating_axes.py::test_curvelinear4[png]` fails on macOS
- `test_grid_helper_curvelinear.py::test_axis_direction[png]` fails on
  ARM and macOS
- `test_grid_helper_curvelinear.py::test_polar_box[png]` fails on
  Windows, ARM, and macOS

These fail on macOS; there's a tolerance on them already, they fail by
just a small amount, so increase it.

- `test_patheffects.py::test_collection[png]`
- `test_axes3d.py::test_scale3d_artists_log[png]`

Since Helvetica may or may not be installed, the line height measurement
may differ between systems, so multi-line text as in this test may
change.

This test doesn't care about line heights, but is about using PDF's
"standard" fonts, so we'll just manually place the lines.

Unfortunately, since text placement still depends on the exact split of
ascent/descent, we still need to add some increased tolerance here.

This will be fixed when all backends correctly apply font metrics for
line height, and PDF can arrange to use our bundled core 14 font
metrics for that.