Update dependencies and commit composer.lock

With composer.lock in the project CI will build against a known set of
dependencies which will make it easier for testing as we'll know if a
failed test is related to our changes. At the moment, the failure could
be because of a dependency's changes.

.gitignore

@@ -1,6 +1,5 @@
-.idea/
-.vendor/
-composer.lock
-vendor/
-/.tmp
-*.cache
+.idea/
+.vendor/
+vendor/
+/.tmp
+*.cache

composer.json

@@ -44,7 +44,7 @@
         "adriansuter/php-autoload-override": "^1.4",
         "laminas/laminas-diactoros": "^2.17",
         "nyholm/psr7": "^1.5",
-        "php-http/psr7-integration-tests": "dev-master",
+        "php-http/psr7-integration-tests": "1.1.1",
         "phpstan/phpstan": "^1.9",
         "phpunit/phpunit": "^9.5",
         "squizlabs/php_codesniffer": "^3.7"