Update doctrine/cache requirement from ^1.8 to ^1.8 || ^2.0

Updates the requirements on [doctrine/cache](https://github.com/doctrine/cache) to permit the latest version.
- [Release notes](https://github.com/doctrine/cache/releases)
- [Commits](doctrine/cache@v1.8.0...2.0.0)

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

Author: dependabot[bot]

composer.json

@@ -14,7 +14,7 @@
         "webonyx/graphql-php": "^0.13.4",
         "psr/container": "^1",
         "doctrine/annotations": "^1.7.0",
-        "doctrine/cache": "^1.8",
+        "doctrine/cache": "^1.8 || ^2.0",
         "thecodingmachine/class-explorer": "^1.1.0",
         "psr/simple-cache": "^1",
         "phpdocumentor/reflection-docblock": "^4.3 || ^5.0",