Add support for nightly-6.2 on Linux in swift_package_test.yml

Since 6.2 development snapshots are already available, it's worth including those in the Linux build matrix

Author: MaxDesiatov

.github/workflows/swift_package_test.yml

@@ -22,7 +22,7 @@ on:
       linux_swift_versions:
         type: string
         description: "Include Linux Swift version list (JSON)"
-        default: "[ \"5.9\", \"5.10\", \"6.0\", \"6.1\", \"nightly-main\", \"nightly-6.1\"]"
+        default: "[ \"5.9\", \"5.10\", \"6.0\", \"6.1\", \"nightly-main\", \"nightly-6.1\", \"nightly-6.2\"]"
       linux_exclude_swift_versions:
         type: string
         description: "Exclude Linux Swift version list (JSON)"