Fix Rails/RootPathnameMethods autocorrection for Pathname calls without parens

[gsamokovarov]

# I run into case where...
file = File.open Rails.root.join 'spec', 'fixtures', 'pdfs', 'read_only.pdf'

# Got autocrrected to... 👇
file = Rails.root.join 'spec', 'fixtures', 'pdfs', 'read_only.pdf'.open

This autocorrection is invalid Ruby code. We can avoid it if we parenthesize Pathname methods before chaining like so:

file = Rails.root.join('spec', 'fixtures', 'pdfs', 'read_only.pdf').open

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[koic]

Thank you,Genadi!