Update hamcrest2 requirement from 0.2.3 to 0.3.0 in /spdk-rs

[dependabot-preview]

Updates the requirements on hamcrest2 to permit the latest version.

Changelog

Sourced from hamcrest2's changelog.

0.3.0 ☰

• Full support for Rust 2018 edition. No more #[macro_use] or deprecation
  warnings for modern idioms. This might have broken some usage of APIs that
  have been deprecated for many months now, thus bumping to 0.3.0. #10

0.2.6 ☰

• The previous version introduced support for reference arguments and this
  broke equal_to for slices. Thus, automatic ref argument support for
  equal_to has been reverted.

0.2.4 ☰

• contains matcher is now generic and supports both collection and single item
  arguments; thus, both contains(vec![5]) and contains(5) work
• Almost all matchers now support reference arguments as well!

0.2.3 ☰

• contains, empty and len matchers now work for slices, not just vectors

0.2.2 ☰

• Added the empty matcher

0.2.1 ☰

• Better message for expected output for ok, err, some and none matchers

0.2.0 ☰

• Created real crate docs with doctests
• added ok and err matchers
• of_len! is now len!
• any_of! is now any!
• all_of! is now all!
• existing_path is now path_exists
• existing_file is now file_exists
• existing_dir is now dir_exists

0.1.6 ☰

• Shorter names for common matchers:
  • eq for equal_to
  • lt for less_than
  • gt for greater_than
  • similarly, geq, leq etc
• Restructured examples in README to reduce verbosity
• Added some matcher
• Added has matcher (like contains but for Option and Result!)

... (truncated)

Commits

• 16bbfe8 Releasing 0.3.0
• ff558fc rustfmt run
• 1a1a74c Removing needless clone() calls
• 0e30adc Removing need for #[macro_use]
• 8af3c58 More rustfmt fixes
• da91658 Fixing more clippy warnings
• 833863b Adding clippy checks in travis
• 3731fe3 Fixing latest clippy warnings
• 77479ad Updating to rust 2018 edition
• 1112990 cargo fmt run
• Additional commits viewable in compare view

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