CI: Don't treat phpdoc types as certain for phpstan

This fixes a phpstan error about the instanceof check for
AnalyticsDetailLevels to always be true. We can't know this
in the code, because they are stored in an array, and it's
conceivable that wrong values could enter here.

Author: pprkut

tests/phpstan.neon.dist

@@ -3,6 +3,7 @@
 
 parameters:
     level: 10
+    treatPhpDocTypesAsCertain: false
     paths:
         - ../src
     bootstrapFiles: