Maintenance: fix all the new clippy warnings

[lukechu10]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 86.66667% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 60.46%. Comparing base (cddfe95) to head (ab74cdf).

Files	Patch %	Lines
packages/sycamore-reactive/src/iter.rs	92.30%	1 Missing ⚠️
packages/sycamore-web/src/dom_node.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #666      +/-   ##
==========================================
+ Coverage   60.45%   60.46%   +0.01%     
==========================================
  Files          54       54              
  Lines        8539     8542       +3     
==========================================
+ Hits         5162     5165       +3     
  Misses       3377     3377              

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