Update lbfgs requirement from 0.2 to 0.3

Updates the requirements on [lbfgs](https://github.com/korken89/lbfgs-rs) to permit the latest version.
- [Release notes](https://github.com/korken89/lbfgs-rs/releases)
- [Changelog](https://github.com/korken89/lbfgs-rs/blob/master/CHANGELOG.md)
- [Commits](korken89/lbfgs-rs@v0.2.0...v0.3.0)

---
updated-dependencies:
- dependency-name: lbfgs
  dependency-version: 0.3.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Cargo.toml

@@ -80,7 +80,7 @@ rustdoc-args = ["--html-in-header", "katex-header.html"]
 num = "0.4"
 
 # Our own stuff - L-BFGS: limited-memory BFGS directions
-lbfgs = "0.2"
+lbfgs = "0.3"
 
 # Instant is a generic timer that works on Wasm (with wasm-bindgen)
 instant = { version = "0.1" }