Add phpstan.dist.neon to export-ignore in .gitattributes

[sasezaki]

Current archive targets other than src/ will be as follows:

gh api repos/php-embed/Embed/tarball/HEAD | tar -tzf - | cut -d/ -f2- | sed '/^$/d' | grep -vE '^src/' | sort

CHANGELOG.md
composer.json
LICENSE
phpstan.dist.neon
README.md

With this PR, the archive targets other than src/ will be as follows:

gh api repos/sasezaki/Embed/tarball/patch-gitattributes | tar -tzf - | cut -d/ -f2- | sed '/^$/d' | grep -vE '^src/' | sort

CHANGELOG.md
composer.json
LICENSE
README.md

Changes:

• Added /phpstan.dist.neon export-ignore

[oscarotero]

I know this is not very important, but can you move the line to 10th position? This way all export-ignore lines are together.

[sasezaki]

sorry, I unintentionally deleted the branch for this pull request and closed it. I would create a new pull request. #571