Fix #189 LDC1.32でCIが動かないためコンパイラバージョンを固定する

[shoo]

1.34.0にて改善されたため、一時的にバージョンを固定していたもの解除する。
また、 #198 の回避策として、一時的に vibe.d のテスト対象から MacOS を外した。
ついでに #192 と #193 の競合を解決する。

[codecov-commenter]

Codecov Report

Merging #200 (b250da2) into master (af59b78) will increase coverage by 0.06%.
Report is 8 commits behind head on master.
The diff coverage is 100.00%.

❗ Current head b250da2 differs from pull request most recent head 2056771. Consider uploading reports for the commit 2056771 to get more accurate results

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@@            Coverage Diff             @@
##           master     #200      +/-   ##
==========================================
+ Coverage   97.34%   97.41%   +0.06%     
==========================================
  Files          41       41              
  Lines        2258     2318      +60     
==========================================
+ Hits         2198     2258      +60     
  Misses         60       60              

Files Changed	Coverage Δ
source/datetime_example.d	100.00% <100.00%> (ø)
thirdparty/vibe-d/source/vibed_usage/rest.d	96.49% <100.00%> (ø)

... and 1 file with indirect coverage changes

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