Fix some issues reported by lintian

Fix some issues reported by lintian

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

• Update standards version to 4.6.1, no changes needed. (out-of-date-standards-version)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/metamath/f586bb44-4f7f-4d7e-8bb8-9a560bcd5eb1.

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/b9/f8bae075f2418b3ba09b992a7fefce45dee625.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/7d/5aef9d8200a542402694d0368c5d4e290b941c.debug

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

• Depends: libc6 (>= 2.14) 2.34)
• Homepage: [-http​://us.metamath.org/-] {+https​://us.metamath.org/+}

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

• Build-Ids: 7d5aef9d8200a542402694d0368c5d4e290b941c b9f8bae075f2418b3ba09b992a7fefce45dee625

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