Update psr/http-message requirement from ^1.0 to ^2.0 (#80)

* Update psr/http-message requirement from ^1.0 to ^2.0

Updates the requirements on [psr/http-message](https://github.com/php-fig/http-message) to permit the latest version.
- [Release notes](https://github.com/php-fig/http-message/releases)
- [Changelog](https://github.com/php-fig/http-message/blob/master/CHANGELOG.md)
- [Commits](php-fig/http-message@1.0...2.0)

---
updated-dependencies:
- dependency-name: psr/http-message
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

* Update composer.json

* Update CHANGELOG.md

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Sergei Predvoditelev <sergei@predvoditelev.ru>

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## 2.0.1 under development
 
-- no changes in this release.
+- Enh #80: Add support for `psr/http-message` version `^2.0` (@vjik)
 
 ## 2.0.0 February 15, 2023
 

composer.json

@@ -21,7 +21,7 @@
         "php": "^7.4|^8.0",
         "ext-dom": "*",
         "ext-json": "*",
-        "psr/http-message": "^1.0",
+        "psr/http-message": "^1.0|^2.0",
         "psr/http-server-middleware": "^1.0",
         "yiisoft/http": "^1.2",
         "yiisoft/json": "^1.0",