Add blog post for FerretDB v1.3.0

[Fashander]

Description

Readiness checklist

• I added/updated unit tests.
• I added/updated integration/compatibility tests.
• I added/updated comments and checked rendering.
• I made spot refactorings.
• I updated user documentation.
• I ran task all, and it passed.
• I ensured that PR title is good enough for the changelog.
• (for maintainers only) I set Reviewers (@FerretDB/core), Labels, Project and project's Sprint fields.
• I marked all done items in this checklist.

[mergify]

Marketing blog posts should be reviewed by @ptrfarkas and @AlekSi.

[codecov]

Codecov Report

Merging #2791 (90f3e96) into main (2397140) will decrease coverage by 36.78%.
The diff coverage is n/a.

❗ Current head 90f3e96 differs from pull request most recent head 2ff281e. Consider uploading reports for the commit 2ff281e to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2791       +/-   ##
===========================================
- Coverage   62.84%   26.07%   -36.78%     
===========================================
  Files         441      441               
  Lines       22740    22740               
===========================================
- Hits        14291     5929     -8362     
- Misses       7517    16201     +8684     
+ Partials      932      610      -322     

see 144 files with indirect coverage changes

Flag	Coverage Δ
integration	4.94% <ø> (-51.38%)	⬇️
mongodb	4.94% <ø> (ø)
pg	?
unit	24.54% <ø> (ø)

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