Release 0.17.2

Released 2024-06-30

• The main branch in git is now main rather than master.
• Update clippy lint usage to get rid of warnings in all code using
  ructe (PR #137). Thanks @vbradl!
• Identified a problem with Content parameters sent through
  intermediate templates, and documented a workaround for it (Issue
  #134, PR #141). Thanks @drehren and @kornelski.
• The axum test is mentioned in [README.md] (PR #138).
  Thanks @abd0-omar!
• Update base64 to 0.22.1 and itertools dependency to 0.13.0.
• MSRV is now 1.61.0.