Bump main to 5.0.0~pre1

[chapulina]

Branch ign-launch4 has been created for the Edifice release and 4.0.0 released from that.

The main branch now corresponds to version 5.0.0~pre1, and nightlies will soon be created from this branch.

gazebo-tooling/release-tools#421

[codecov]

Codecov Report

Merging #106 (8755467) into main (c570131) will not change coverage.
The diff coverage is n/a.

❗ Current head 8755467 differs from pull request most recent head 1b4b24e. Consider uploading reports for the commit 1b4b24e to get more accurate results

@@           Coverage Diff           @@
##             main     #106   +/-   ##
=======================================
  Coverage   30.24%   30.24%           
=======================================
  Files           3        3           
  Lines         734      734           
=======================================
  Hits          222      222           
  Misses        512      512           

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[chapulina]

All CI is 🟢 , this is ready to go!