Bump subxt from a7b45ef to d4545de

Bumps [subxt](https://github.com/paritytech/subxt) from `a7b45ef` to `d4545de`.
- [Release notes](https://github.com/paritytech/subxt/releases)
- [Commits](paritytech/subxt@a7b45ef...d4545de)

---
updated-dependencies:
- dependency-name: subxt
  dependency-type: direct:production
...

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