chore: bump version to 0.6.0 and mark as beta

Finalizes the version number across build files (pyproject.toml and
build.zig.zon) for the 0.6.0 release.

Updates the Python package classifier from Alpha (3) to Beta (4).

Author: arrufat

bindings/python/pyproject.toml

@@ -4,15 +4,15 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "zignal-processing"
-version = "0.6.0.dev"
+version = "0.6.0"
 description = "Zero-dependency image processing library"
 readme = "README.md"
 authors = [{name = "zignal contributors"}]
 license = "MIT"
 requires-python = ">=3.10"
 keywords = ["image-processing", "computer-vision", "zig", "native"]
 classifiers = [
-    "Development Status :: 3 - Alpha",
+    "Development Status :: 4 - Beta",
     "Intended Audience :: Developers",
     "Programming Language :: Python :: 3",
     "Programming Language :: Python :: 3.10",

build.zig.zon

@@ -1,6 +1,6 @@
 .{
     .name = .zignal,
-    .version = "0.6.0-dev",
+    .version = "0.6.0",
     .fingerprint = 0x5303c43db377b63a,
     .minimum_zig_version = "0.16.0-dev.368+2a97e0af6",
     .dependencies = .{},