Update pkg-config requirement from = 0.3.15 to = 0.3.26

Updates the requirements on [pkg-config](https://github.com/rust-lang/pkg-config-rs) to permit the latest version.
- [Release notes](https://github.com/rust-lang/pkg-config-rs/releases)
- [Changelog](https://github.com/rust-lang/pkg-config-rs/blob/master/CHANGELOG.md)
- [Commits](rust-lang/pkg-config-rs@0.3.15...0.3.26)

---
updated-dependencies:
- dependency-name: pkg-config
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Cargo.toml

@@ -9,7 +9,7 @@ serde = {version = "1.0", features = ["derive"]}
 serde_json = "1.0"
 log = "^0.4.0"
 # Pinning this to 0.3.15 due to kubos linux build issues with v0.3.16
-pkg-config = "= 0.3.15"
+pkg-config = "= 0.3.26"
 
 kubos-system = { git = "ssh://git@github.com/Cube-OS/system-api.git"}
 # kubos-system = { path = "../system-api"}