templates: add eslint ignore rule for 'src/migrations/*'

[Rot4tion]

What?

Added a new ignore pattern 'src/migrations/*' to the ESLint configuration to exclude migration files from linting.

Why?

The files inside the src/migrations directory are automatically generated by Payload. These files often trigger ESLint warnings such as:

• Warning: 'payload' is defined but never used.
• Warning: 'req' is defined but never used.

Ignoring this directory prevents unnecessary and irrelevant lint warnings on auto-generated code.

How?

Added the 'src/migrations/*' pattern to the ESLint ignore configuration to prevent linting of migration files.