chore: Pin external actions using hashes

[mathbunnyru]

Note: I used exactly the version which are already being used (didn't update anything).
Updates will come when we merge #2018

[mathbunnyru]

The reason for this change - if someone whose lib we use decides to change their action in a malicious way, we will automatically start using it without even knowing something has changed.

I don't pin github provided actions, because if they are compromised, we are probably done already, and it creates too much noise.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.77%. Comparing base (427ba47) to head (f67d888).
Report is 57 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2019      +/-   ##
===========================================
+ Coverage    72.71%   72.77%   +0.05%     
===========================================
  Files          333      355      +22     
  Lines        13525    14669    +1144     
  Branches      6881     7448     +567     
===========================================
+ Hits          9835    10675     +840     
- Misses        1785     1972     +187     
- Partials      1905     2022     +117     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.