[code-quality] fix clang-tidy cstddef

[tomaszduda23]

What does this implement/fix?

### File /esphome/.temp/all-include.cpp

/esphome/esphome/components/microphone/microphone.h:3:10: error: inclusion of deprecated C++ header 'stddef.h'; consider using 'cstddef' instead [modernize-deprecated-headers,-warnings-as-errors]
#include <stddef.h>
         ^~~~~~~~~~
         <cstddef>
/esphome/esphome/components/speaker/speaker.h:3:10: error: inclusion of deprecated C++ header 'stddef.h'; consider using 'cstddef' instead [modernize-deprecated-headers,-warnings-as-errors]
#include <stddef.h>
         ^~~~~~~~~~
         <cstddef>

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other

Related issue or feature (if applicable): fixes

Pull request in esphome-docs with documentation (if applicable): esphome/esphome-docs#

Test Environment

• ESP32
• ESP32 IDF
• ESP8266
• RP2040
• BK72xx
• RTL87xx

Example entry for config.yaml:

# Example config.yaml

Checklist:

• The code change is tested and works locally.
• Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in esphome-docs.

[probot-esphome]

Hey there @jesserockz, mind taking a look at this pull request as it has been labeled with an integration (microphone) you are listed as a code owner for? Thanks!
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[probot-esphome]

Hey there @jesserockz, mind taking a look at this pull request as it has been labeled with an integration (speaker) you are listed as a code owner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 53.95%. Comparing base (4d8b5ed) to head (f85b8a8).
Report is 1186 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #7324      +/-   ##
==========================================
+ Coverage   53.70%   53.95%   +0.24%     
==========================================
  Files          50       50              
  Lines        9408     9665     +257     
  Branches     1654     1706      +52     
==========================================
+ Hits         5053     5215     +162     
- Misses       4056     4126      +70     
- Partials      299      324      +25     

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[jesserockz]

Huh, interesting as when I changed these recently it was complaining it could not find size_t without the stddef.h. I tried cstddef but it was not working at the time. Maybe a cache thing.

[nielsnl68]

Huh, interesting as when I changed these recently it was complaining it could not find size_t without the stddef.h. I tried cstddef but it was not working at the time. Maybe a cache thing.

I saw this behavier also popping up while i was doing the changes on the speaker.h file etc.