chore(php): add deprecation warning for php 8.0 (#353)

* chore(php): Add deprecation warning for php 8.0

Refs: #343

* docs(php): add information about supported php versions

Author: Xenira

README.md

@@ -22,9 +22,9 @@ Export a simple function `function hello_world(string $name): string` to PHP:
 use ext_php_rs::prelude::*;
 
 /// Gives you a nice greeting!
-/// 
+///
 /// @param string $name Your name.
-/// 
+///
 /// @return string Nice greeting!
 #[php_function]
 pub fn hello_world(name: String) -> String {
@@ -114,8 +114,12 @@ best resource at the moment. This can be viewed at [docs.rs].
 ## Requirements
 
 - Linux, macOS or Windows-based operating system.
-- PHP 8.0 or later.
+- PHP 8.1 or later.
   - No support is planned for earlier versions of PHP.
+  - PHP versions, that no longer receive security updates, will no longer be
+    supported. They might still work, but no guarantees are made.
+  - See <https://www.php.net/supported-versions.php> for information on PHP
+    supported versions and their end of life dates.
 - Rust.
   - Currently, we maintain no guarantee of a MSRV, however lib.rs suggests Rust
     1.57 at the time of writing.

build.rs

@@ -237,6 +237,10 @@ fn check_php_version(info: &PHPInfo) -> Result<()> {
     );
     println!("cargo:rustc-cfg=php80");
 
+    if (MIN_PHP_API_VER..PHP_81_API_VER).contains(&version) {
+        println!("cargo:warning=PHP version 8.0 is EOL and will no longer be supported in a future release. Please upgrade to a supported version of PHP. See https://www.php.net/supported-versions.php for information on version support timelines.");
+    }
+
     if (PHP_81_API_VER..PHP_82_API_VER).contains(&version) {
         println!("cargo:rustc-cfg=php81");
     }