Merge bitcoindevkit/bdk#2073: ci: automated update to rustc 1.91.1

Merge bitcoindevkit/bdk#2073: ci: automated update to rustc 1.91.1

1752c433177377400fe2ba3cbf3a5c63cb5f050e ci: automated update to rustc 1.91.1 (Github Action)

Pull request description:

  Automated update to Github CI workflow `cont_integration.yml` by [create-pull-request](https://github.com/peter-evans/create-pull-request) GitHub action

ACKs for top commit:
  ValuedMammal:
    ACK 1752c433177377400fe2ba3cbf3a5c63cb5f050e

Tree-SHA512: 08e18752b59407323077f190fd3fa6dbafd2d8f3c1fccceff4a48d1d186b9354d9fdca197920ef934df2411b3ab325ade100c0993238c0c195b432acd8e6a99d