ICU-21957 BRS72RC Update version number and regenerate configure v72.1

[rp9-next]

Checklist

• Required: Issue filed: https://unicode-org.atlassian.net/browse/ICU-21957
• Required: The PR title must be prefixed with a JIRA Issue number.
• Required: The PR description must include the link to the Jira Issue, for example by completing the URL in the first checklist item
• Required: Each commit message must be prefixed with a JIRA Issue number.
• Issue accepted (done by Technical Committee after discussion)
• Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable

[markusicu]

FYI For ICU pull requests, we set the assignee to the main reviewer, not to the PR author. The PR author is obviously doing the work already :-)
See https://icu.unicode.org/repository/gitdev

[markusicu]

lgtm tnx