fix: use c++ 17

[winstxnhdw]

Closes #1190
Closes #1184
Closes #1178

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 14 lines in your changes missing coverage. Please review.

Project coverage is 46.93%. Comparing base (19654bf) to head (513caa0).

Files	Patch %	Lines
crates/engine_spx2html/src/fontfile.rs	0.00%	6 Missing ⚠️
crates/engine_spx2html/src/fonts.rs	0.00%	4 Missing ⚠️
crates/engine_spx2html/src/initialization.rs	0.00%	2 Missing ⚠️
crates/engine_spx2html/src/assets.rs	0.00%	1 Missing ⚠️
crates/xdv/src/lib.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1202      +/-   ##
==========================================
- Coverage   46.99%   46.93%   -0.06%     
==========================================
  Files         176      177       +1     
  Lines       65196    65191       -5     
==========================================
- Hits        30639    30599      -40     
- Misses      34557    34592      +35     

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[CraftSpider]

Thank you for your work on this! I'll merge this once I find time to review it.

[winstxnhdw]

FWIW, it is working fine on my project.

[CraftSpider]

I'm not worried about the coverage failure personally - a decrease of .06 isn't really a big deal, and the clippy fixes I'm guessing just altered line hits slightly.