Install libnss3 in order to fix .pdf -> .mobi

[itsthejb]

Description:

• Resolves Calibre failed with error: /app/calibre/bin/pdftohtml: error while loading shared libraries: libnss3.so: cannot open shared object file #55
• Converting .pdf to something, for example .mobi seems like a general-purpose feature/fix, so submitting a patch

Benefits of this PR and context:

• Ability to convert .pdf to .mobi, or even .epub

How Has This Been Tested?

• Add a .pdf, example https://web.mit.edu/alexmv/6.037/sicp.pdf
  • Not sure of the general case
• Try Edit metadata, convert to .mobi
• Will fail in logs with ERROR in worker: Calibre failed with error: /app/calibre/bin/pdftohtml: error while loading shared libraries: libnss3.so: cannot open shared object file: No such file or directory
  • Installing libnss3 for this support seems like a trivial fix
• Install the library manually; apt-get install libnss3
• Repeat test process
• Conversion succeeds

Source / References:

• Issue Calibre failed with error: /app/calibre/bin/pdftohtml: error while loading shared libraries: libnss3.so: cannot open shared object file #55, fix suggested by @hholst80

[CHBMB]

@itsthejb Can you also add it to Dockerfile.aarch64 and Dockerfile.armhf as well to cover the other architectures.

No need for && it's all one command, that will break the Dockerfile.

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/calibre-web/0.6.4-pkg-fe11335c-pr-56/index.html
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/calibre-web/0.6.4-pkg-fe11335c-pr-56/shellcheck-result.xml

[itsthejb]

@CHBMB ok, will do

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/calibre-web/0.6.4-pkg-fe11335c-pr-56/index.html
https://lsio-ci.ams3.digitaloceanspaces.com/lspipepr/calibre-web/0.6.4-pkg-fe11335c-pr-56/shellcheck-result.xml