Invoke load_spawn_weights() only in proc with rank 0

[areshytko]

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?
• If you made a notable change (that affects users), did you update the CHANGELOG?

What does this PR do?

Fixes #1335 .

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

[williamFalcon]

@areshytko awesome! there seems to be a failing doc test @Borda.

[Borda]

yes, pls rebase master

[codecov]

Codecov Report

Merging #1385 into master will increase coverage by 0%.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #1385   +/-   ##
======================================
  Coverage      92%     92%           
======================================
  Files          63      63           
  Lines        3330    3332    +2     
======================================
+ Hits         3057    3059    +2     
  Misses        273     273           

[Borda]

missing changelog