[MCC-1977] Fix dependabot parsing issue

[kylefleming]

Motivation

Dependabot is failing with the following error:

Dependabot couldn't parse the Cargo.toml found at /sgx/epid-types/Cargo.toml.

The error Dependabot encountered was:

Dependabot::DependencyFileNotParseable

(see: https://github.com/mobilecoinofficial/mobilecoin/network/updates/65925226)

Running it locally reveals the underlying issue:

/home/dependabot/dependabot-script/vendor/ruby/2.6.0/gems/citrus-3.0.2/lib/citrus.rb:669:in `parse': Failed to parse input on line 32 at offset 43 (Citrus::ParseError)
bytes = { version = "0.5", optional = true , default-features = false}

                                           ^

In this PR

• Fixes a parsing issue with sgx/epid-types/Cargo.toml

Fixes MCC-1977

[cbeck88]

thank you!