Fix some issues reported by lintian

Fix some issues reported by lintian

• Use secure copyright file specification URI. (insecure-copyright-format-uri)

• Use secure URI in Homepage field. (homepage-field-uses-insecure-uri)

• Bump debhelper from deprecated 9 to 10. (package-uses-deprecated-debhelper-compat-version)

This merge proposal was created automatically by the Janitor bot. For more information, including instructions on how to disable these merge proposals, see https://janitor.debian.net/lintian-fixes.

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Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/prooftree/d7be7c05-4fed-4bd2-92c8-8ab1c002580a.

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 set of .debs but not in first

-rw-r--r--  root/root   /usr/lib/debug/.build-id/ba/f0d6532c69d341c63479539079d08a642c7512.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/57/17229d849468d7a66089f8931e6e68fc1bee60.debug

Control files of package prooftree: lines which differ (wdiff format)

• Homepage: [-http​://askra.de/software/prooftree-] {+https​://askra.de/software/prooftree+}

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

• Build-Ids: 5717229d849468d7a66089f8931e6e68fc1bee60 baf0d6532c69d341c63479539079d08a642c7512

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