libcnb-data v0.5.0

• Add #[must_use] to BuildPlan and BuildPlanBuilder (#288).
• Add exec_d module with types representing the output of an exec.d program (#324).
• Increase minimum supported Rust version from 1.56 to 1.58 (#318).
• Adjust newtype generated compile-time validation macros so that they don't also perform redundant validation at runtime. In cases where only compile-time validation is being performed (for example exec.d scripts), this results in a significant reduction in binary size. (#331)
• Update libcnb-proc-macros from 0.1.1 to 0.2.0 - see the libcnb-proc-macros changelog. (#361)