Filter phantom_generics to contain types only

[danielalvsaaker]

Fixes #311.

[codecov-commenter]

Codecov Report

Merging #312 (136690a) into master (7738584) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #312      +/-   ##
==========================================
+ Coverage   73.21%   73.28%   +0.07%     
==========================================
  Files          38       38              
  Lines        5313     5320       +7     
==========================================
+ Hits         3890     3899       +9     
+ Misses       1423     1421       -2     

Impacted Files	Coverage Δ
packages/sycamore-macro/src/component/mod.rs	76.25% <100.00%> (+0.78%)	⬆️
packages/sycamore-reactive/src/effect.rs	91.30% <0.00%> (+0.26%)	⬆️

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[lukechu10]

Thanks!