Support ESLint v10: use context.filename instead of removed context.getFilename()

[takeshi-biz]

Problem

ESLint v10 removed the deprecated context.getFilename() (along with other legacy RuleContext methods).

strict-dependencies/index.js calls context.getFilename() directly, so the rule throws TypeError: context.getFilename is not a function on every lint run under ESLint v10, making the plugin unusable on v10.

Fix

Use context.filename (available since ESLint v8.40) and fall back to context.getFilename() for older versions:

const fileFullPath = context.filename ?? context.getFilename()

This keeps full backward compatibility:

• ESLint < 8.40 (no context.filename) → falls back to context.getFilename()
• ESLint 8.40 – 9.x → uses context.filename (getFilename() still works but is deprecated)
• ESLint 10.x → uses context.filename (getFilename() removed)

Test

• Added a test verifying the rule works when context.getFilename is absent (the ESLint v10 case), i.e. only context.filename is provided.
• All existing tests pass unchanged — their mock context provides getFilename but not filename, so the fallback path is still exercised.

npm test → 35 passed.