Increase psalm level to 4 and corresponding changes

[vjik]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	✔️

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (d39ffff) 76.08% compared to head (8e008e6) 74.54%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #242      +/-   ##
============================================
- Coverage     76.08%   74.54%   -1.55%     
+ Complexity      585      583       -2     
============================================
  Files            48       48              
  Lines          2024     2023       -1     
============================================
- Hits           1540     1508      -32     
- Misses          484      515      +31     

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[what-the-diff]

PR Summary

• Composer File version update
  The project dependencies are handled using a tool called Composer. In this PR, the version for a package called vimeo/psalm has been updated. This modification helps in keeping the codebase up-to-date and might bring new features or bug fixes from the package.

• Attribute Modification in Psalm Configuration
  Psalm is a tool used for static analysis of code. The errorLevel attribute in the configuration file has been adjusted. This change adjusts the strictness of the analysis, possibly making code checks more rigorous ensuring high code quality.

• Code Adjustment in Command Collector
  Changes were made in how the CommandCollector handles different types of events. This enhancement ensures that the system performs ​correctly, no matter what the event type is.

• Class and Type Hint Modification
  Updates were made to two classes, FilesystemStreamProxy and HttpStreamProxy. The classes were marked as final (meaning that they cannot be subclassed), and the data type for the decorated property was changed. These updates bring certainty about the behaviors of these classes, facilitating safer code.

• Function check removal in Request Collector
  An object type verification in the collect function of RequestCollector.php was removed. This update may make the function operate more efficiently and might have decreased code redundancy.

• Annotation Addition in Stream Wrapper
  An instruction (annotation) was added to a condition in the StreamWrapper, indicating that the condition redundancy warning should be ignored by Psalm tool. This annotation serves as a pointer to intentionally left redundancy, possibly in order to handle specific situations.