Enhancement: Add SECURITY.md (#739)

Author: localheinz

.github/SECURITY.md

@@ -0,0 +1,17 @@
+# Security Policy
+
+## Supported Versions
+
+The following versions of `fakerphp/faker` have active support:
+
+- `^1.23.0`
+
+## Unsupported Versions
+
+The following versions of `fakerphp/faker` have reached their end of life:
+
+- `<1.23.0`
+
+## Reporting a Vulnerability
+
+If you believe that you have found a security vulnerability, please send an email to security@fakerphp.org. Ensure to include all details required to understand the severity of the issue.