Update rsa requirement from ^0.6.0 to ^0.7.1

Updates the requirements on [rsa](https://github.com/RustCrypto/RSA) to permit the latest version.
- [Release notes](https://github.com/RustCrypto/RSA/releases)
- [Changelog](https://github.com/RustCrypto/RSA/blob/master/CHANGELOG.md)
- [Commits](RustCrypto/RSA@v0.6.0...v0.7.1)

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

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -33,7 +33,7 @@ num-integer = { version = "^0.1.44", optional = true }
 num-traits = { version = "^0.2.14", optional = true }
 rand = { version = "^0.8.4", optional = true }
 sha2 = { version = "0.10.2", optional = true }
-rsa = { version = "^0.6.0", optional = true }
+rsa = { version = "^0.7.1", optional = true }
 
 [target.'cfg(target_arch = "x86_64")'.dependencies]
 xsave = { version = "^2.0.0", default-features = false }