Update symfony/filesystem from v3.4.14 to v3.4.39

[violinist-bot]

If you have a high test coverage index, and your tests for this pull request are passing, it should be both safe and recommended to merge this update.

Here is a list of changes between the version you use, and the version this pull request updates to:

• ec47520 Fix quotes in exception messages
• 68623e9 Add missing dots at the end of exception messages
• 0a0d3b4 chown and chgrp should also accept int as owner and group
• 1d5b4fe Update links to documentation
• c03aaa3 Update year in license files
• 00cdad0 [Filesystem] [Serializer] fixes English grammar typo
• 00e3a6d Fix inconsistent return points.
• 46b3a57 Fix some docblocks.
• 10661ec Fix return statements
• f1b75e0 minor #32800 Improve some URLs (Arman-Hosseini)
• 87e6a90 Improve some URLs
• 00f360d Use PHPunit assertion
• 9935d12 cs fix
• ea51409 Remove use of ForwardCompatTrait
• d7ca582 Fix deprecated phpunit annotation
• 78ec64d Make tests support phpunit 8
• 70adda0 add test to avoid regressions
• 44fa9ca fixed CS
• acf9975 [Filesystem] Fixed some docblocks and typos
• b52454e fixed short array CS in comments
• 1920c50 switched array() to []
• c24ce3d update year in license files
• b49b1ca Merge branch '2.8' into 3.4
• 7ae4687 Bump phpunit XSD version to 5.2
• d69930f Merge branch '2.8' into 3.4
• 56a9248 [CS] Enforces null type hint on last position in phpDocs
• f89ab24 Merge branch '2.8' into 3.4
• 91f194c [Filesystem] Skip tests on readable file when run with root user
• 68bc3e4 Merge branch '2.8' into 3.4
• 07205db Consistently throw exceptions on a single line
• 81d3c01 Merge branch '2.8' into 3.4
• 7b4b283 Fix appveyor
• 34965c4 Merge branch '2.8' into 3.4
• 37a3837 Use the real image URL for the filesystem tests
• 285ce50 Merge branch '2.8' into 3.4
• 0b252f4 [Filesystem] Add test to prevent regression when using array|resource with dumpFile

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