Fix some issues reported by lintian

Fix some issues reported by lintian

• Trim trailing whitespace. (file-contains-trailing-whitespace)
• Use secure copyright file specification URI. (insecure-copyright-format-uri)
• Use secure URI in debian/watch. (debian-watch-uses-insecure-uri)
• Explicitly specify source format. (missing-debian-source-format)
• Bump debhelper from deprecated 7 to 10. (package-uses-deprecated-debhelper-compat-version)
• Fix field name typos in debian/copyright. (field-name-typo-dep5-copyright)

This merge proposal was created automatically by the Janitor bot.

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Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/cachefilesd/ebdae851-c4ac-4fc5-9fca-8ef2eea2bcb6.

Debdiff

These changes affect the binary packages:

[The following lists of changes regard files as different if they have different names, permissions or owners.]

Files in second .changes but not in first

-rw-r--r--  root/root   /usr/lib/debug/.build-id/9d/6c05a8d359191d4786d9d2ca49ca2a7b5a7e41.debug

Files in first .changes but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/33/b561d634c2626ad594bb8ec3bd281dc1ecdff0.debug

No differences were encountered between the control files of package **cachefilesd**

Control files of package cachefilesd-dbgsym: lines which differ (wdiff format)

• Build-Ids: 33b561d634c2626ad594bb8ec3bd281dc1ecdff0 9d6c05a8d359191d4786d9d2ca49ca2a7b5a7e41

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