Bump module to 0.15.0 (#158)

Author: srueg

MODULE.bazel

@@ -16,7 +16,7 @@
 
 module(
     name = "rules_pkl",
-    version = "0.14.0",
+    version = "0.15.0",
     bazel_compatibility = [">=7.0.0"],
     compatibility_level = 1,
 )

README.md

@@ -18,7 +18,7 @@ To use `rules_pkl`, enable `bzlmod` within your project, and then add the follow
 
 ```starlark
 # Please check the releases page on GitHub for the latest released version
-bazel_dep(name = "rules_pkl", version = "0.14.0")
+bazel_dep(name = "rules_pkl", version = "0.15.0")
 ```
 
 ## Examples