chore: bump version to 4.0.0 [version bump]

Author: github-actions[bot]

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 4.0.0 - 2026-01-09
+
+* [Full Changelog](https://github.com/PostHog/posthog-php/compare/3.7.3...4.0.0)
+
 3.7.3 / 2025-12-04
 ==================
 
@@ -259,7 +263,8 @@
   * Merge pull request #6 from chuva-inc/document_property
   * Merge pull request #5 from chuva-inc/issue_4
   * Posthog/posthog-php#3: Document the customer property
-  * PostHog/posthog-php#4: Removes \n from beginning of the file
+  * PostHog/posthog-php#4: Removes 
+ from beginning of the file
   * Update README.md
   * fix infinite loop on error 0 from libcurl
   * fix error when including https:// in host

composer.json

@@ -1,6 +1,6 @@
 {
 	"name": "posthog/posthog-php",
-	"version": "3.7.3",
+	"version": "4.0.0",
 	"description": "PostHog PHP Library",
 	"keywords": [
 		"posthog"

lib/PostHog.php

@@ -6,7 +6,7 @@
 
 class PostHog
 {
-    public const VERSION = '3.7.3';
+    public const VERSION = '4.0.0';
     public const ENV_API_KEY = "POSTHOG_API_KEY";
     public const ENV_HOST = "POSTHOG_HOST";