Remove and old check that's no longer useful

Before migration to DocC, the old publication pipeline ran these tests,
so this test would fail if we forgot to update the version number for a
new Swift version.  That was a useful way to help make sure this chapter
got updated.  Now that we've building TSPL with DocC, and therefore no
longer able to run the tests, there's likewise no longer any reason to
keep this test around.

Author: amartini51

TSPL.docc/GuidedTour/Compatibility.md

@@ -7,21 +7,6 @@ the default version of Swift that's included in Xcode 15.1.
 You can use Xcode 15.1 to build targets
 that are written in either 5.10, Swift 4.2, or Swift 4.
 
-<!--
-  - test: `swift-version`
-
-  ```swifttest
-  >> #if swift(>=5.9.3)
-  >>     print("Too new")
-  >> #elseif swift(>=5.9.2)
-  >>     print("Just right")
-  >> #else
-  >>     print("Too old")
-  >> #endif
-  << Just right
-  ```
--->
-
 When you use Xcode 15.1 to build Swift 4 and Swift 4.2 code,
 most Swift 5.10 functionality is available.
 That said,