Enable the @typescript-eslint/no-unsafe-argument eslint rule (#1831)

## Description:

Enable the `@typescript-eslint/no-unsafe-argument` eslint rule.

Fixes #1780

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

src/client/LanguageModal.ts

@@ -106,7 +106,9 @@ export class LanguageModal extends LitElement {
               return html`
                 <button
                   class="${buttonClasses}"
-                  @click=${() => this.selectLanguage(lang.code)}
+                  @click=${() =>
+                  // eslint-disable-next-line @typescript-eslint/no-unsafe-argument
+                    this.selectLanguage(lang.code)}
                 >
                   <img
                     src="/flags/${lang.svg}.svg"