Bump aioesphomeapi to 21.0.2

[bdraco]

needs https://github.com/esphome/aioesphomeapi/actions/runs/7804166800

What does this implement/fix?

Removes cryptography from requirements_optional.txt and adds it to requirements.txt as its not optional since aioesphomeapi needs it for noise.

Its important we pin cryptography because it tends to have breaking changes and we see problems like home-assistant/core#109804

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.