De-blob serde

[pinkforest]

Fixes #1218

I've been advocating to get serde to do the binary blobs opt-in basis but at best there will be opt-out at top bin level only :(

This will restrict the max version to ensure only serde without binary blobs gets pulled

Crates time and rust-analyzer have already done this and rand etc. may follow as well soon.

[codecov]

Codecov Report

Merging #1219 (0d13243) into 0.4.x (0be4e7c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##            0.4.x    #1219   +/-   ##
=======================================
  Coverage   86.14%   86.14%           
=======================================
  Files          37       37           
  Lines       13394    13394           
=======================================
  Hits        11538    11538           
  Misses       1856     1856           

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[pitdicker]

Downstream users can choose to restrict the maximum version of a dependency, this does not have to be done in chrono. Let's leave the choice up to them.