Make ZygoteRules and ChainRulesCore weak dependencies

[devmotion]

IMO these overloads in the compat subfolder are natural candidates for a weak dependency.

[github-actions]

Pull Request Test Coverage Report for Build 6947129998

• 7 of 8 (87.5%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+1.3%) to 81.55%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
ext/DynamicPPLZygoteRulesExt.jl	4	5	80.0%

Totals
Change from base Build 6947084016:	1.3%
Covered Lines:	2568
Relevant Lines:	3149

---

💛 - Coveralls

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (03e4ba2) 80.26% compared to head (b28f6bb) 81.00%.

Files	Patch %	Lines
ext/DynamicPPLZygoteRulesExt.jl	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #564      +/-   ##
==========================================
+ Coverage   80.26%   81.00%   +0.74%     
==========================================
  Files          26       26              
  Lines        3167     3170       +3     
==========================================
+ Hits         2542     2568      +26     
+ Misses        625      602      -23     

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[torfjelde]

LGTM! One thing though: do we know why compat is complaining? Or is codecov only run on Julia 1.9?

[devmotion]

Coverage analysis was only performed on Julia 1.9.

[devmotion]

Good to go, @torfjelde?

[torfjelde]

Aye:)