Update cam-geom requirement from 0.14 to 0.15

Updates the requirements on [cam-geom](https://github.com/strawlab/cam-geom) to permit the latest version.
- [Commits](strawlab/cam-geom@0.14.0...0.15.0)

---
updated-dependencies:
- dependency-name: cam-geom
  dependency-type: direct:production
...

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

dlt-examples/Cargo.toml

@@ -9,6 +9,6 @@ repository = "https://github.com/strawlab/dlt"
 
 [dependencies]
 dlt = {path=".."}
-cam-geom = "0.14"
+cam-geom = "0.15"
 nalgebra = "0.32"
 approx = "0.5"