Fix fallout from ttf-parser and svgtypes upgrades

This MR fixes the fallout of MR !714 (merged):

• svgtypes v0.15 introduced a new test which fails on i386, most probably due to the unsoundness of floating point operations in the absence of SSE2. There's nothing much we can do here other than disable the failing test. The difference between the expected and computed result is very small anyway.
• I'd hoped not to need to upgrade owned_ttf_parser together with ttf-parser. Unfortunately, the upgrade makes rusttype's autopkgtests fail because ttf-parser v0.24 introduced a new feature, no-std-float, which must exist in owned_ttf_parser too in order to patch rusttype's features and make the tests pass. Thus we'll do this the clean way and also upgrade owned_ttf_parser to v0.24, together with its rdeps (rusttype itself and ab_glyph).

/cc @eamanu