Fix BibTeX file URL

[y-yu]

Changes made

• Fix URL in BibTeX file

Justification

• Use SSL(https) URL
• Now https://community.qiskit.org/textbook has been moved so I fix it

  $ curl -I https://community.qiskit.org/textbook
  HTTP/2 301
  date: Fri, 29 Jul 2022 04:51:55 GMT
  location: https://qiskit.org/textbook
  expect-ct: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  server: cloudflare
  cf-ray: 73233dffac1914d4-NRT
  

  $ curl -I https://qiskit.org/textbook
  HTTP/2 301
  date: Fri, 29 Jul 2022 04:53:22 GMT
  location: https://qiskit.org/textbook/
  expect-ct: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
  server: cloudflare
  cf-ray: 7323401c8ad7afe1-NRT
  

Discussion

• This repository has another BibTeX file 👀
  • https://github.com/qiskit-community/qiskit-textbook/blob/09212862c48a09c842a1e11d4df339d28a6d6cef/i18n/locales/ja/qiskit-textbook.bib#L1-L8
  • Should I fix also this file?

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