[BUGFIX] Avoid warning when set up extension

[brotkrueml]

When running the command

vendor/bin/typo3 setup:extension -e examples

the following warning was raised:

[WARNING] examples contains data to be imported, but the required component is not installed. Make sure  to define
          corresponding requirements.

This change adds EXT:impexp as dependency requirement.

Resolves: #253
Releases: main, 12.4

[github-actions]

The backport to 12.4 failed:

The process '/usr/bin/git' failed with exit code 1

stderr

error: could not apply 717a30e... [BUGFIX] Avoid warning when set up extension
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".

stdout

Auto-merging composer.json
CONFLICT (content): Merge conflict in composer.json
Auto-merging ext_emconf.php
CONFLICT (content): Merge conflict in ext_emconf.php

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-12.4 12.4
# Navigate to the new working tree
cd .worktrees/backport-12.4
# Create a new branch
git switch --create backport-256-to-12.4
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick 717a30e1b5e4c19f17f3867e8b91450db00abaee,e13ec4ccd8aa673b63b25b595d88bd368ff4b631,25a8238fb633dbe53a77694937b62434212be111,eab145dc149f7d6fdee49426d1fb66181377f66e
# Push it to GitHub
git push --set-upstream origin backport-256-to-12.4
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-12.4

Then, create a pull request where the base branch is 12.4 and the compare/head branch is backport-256-to-12.4.