chore(deps): bump spki from 0.4.0 to 0.4.1 (#453)

Bumps [spki](https://github.com/RustCrypto/formats) from 0.4.0 to 0.4.1.
- [Release notes](https://github.com/RustCrypto/formats/releases)
- [Commits](https://github.com/RustCrypto/formats/commits/spki/v0.4.1)

---
updated-dependencies:
- dependency-name: spki
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

ethers-signers/Cargo.toml

@@ -33,7 +33,7 @@ rusoto_core = { version = "0.47.0", optional = true }
 rusoto_kms = { version = "0.47.0", optional = true }
 tracing = { version = "0.1.27", optional = true }
 tracing-futures = { version = "0.2.5", optional = true }
-spki = { version = "0.4.0", optional = true }
+spki = { version = "0.4.1", optional = true }
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 eth-keystore = { version = "0.3.0" }