fix: negative temperatures on PMS5003T sensors

[aschmitz]

What does this implement/fix?

Fixes negative temperatures on PMS5003T sensors, which had previously been interpreted as unsigned integers.

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 esphome/issues#3814 for the PMS5003T (#6083 fixed it for the PMS5003ST, but missed the 5003T)

Pull request in esphome-docs with documentation (if applicable): No documentation update should be needed.

Test Environment

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

Example entry for config.yaml:

sensor:
  - platform: pmsx003
    type: PMS5003T
    uart_id: uart_pm
    temperature:
      id: pm_temperature
      name: "Temperature"

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.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (8cd1798) 53.68% compared to head (5fddbb7) 53.68%.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev    #6100   +/-   ##
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  Coverage   53.68%   53.68%           
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  Files          50       50           
  Lines        9385     9385           
  Branches     1651     1651           
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  Hits         5038     5038           
  Misses       4048     4048           
  Partials      299      299           

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