fix: Add spanish flag for international spanish

What change does this pull request introduce?

This will change the flag used to represent the Spanish language in the language selection dropdown from the Mexican flag to the Spanish flag.

The Spanish flag is widely recognized as the neutral representation of the Spanish language on global platforms. It ensures consistency with standard international practices and improves user experience by presenting a neutral symbol for the language, regardless of regional differences in dialect.

Checklist

[X] I worked on a branch other than main.
[X] My branch is up-to-date with the Upstream main branch.
[X] I have fixed potential errors using yarn lint.
[X] I ran yarn build to check everything still builds successfully.

TheAlgorithms / website

fix: Add spanish flag for international spanish #298