chromedriver: use platforms versions, fix parse error

www/chromedriver/Portfile

@@ -5,7 +5,8 @@ PortSystem          1.0
 name                chromedriver
 version             136.0.7103.113
 categories          www
-platforms           darwin
+# See: https://trac.macports.org/ticket/67097
+platforms           {darwin >= 20}
 maintainers         nomaintainer
 license             Apache-2
 supported_archs     arm64 x86_64
@@ -28,19 +29,12 @@ if {${os.arch} ni [list arm i386]} {
     }
 }
 
-# See: https://trac.macports.org/ticket/67097
-if {${os.platform} eq "darwin" && ${os.major} < 20} {
-    known_fail      yes
-    pre-fetch {
-        ui_error "${name} @${version} requires macOS 11 or later."
-        return -code error "incompatible macOS version"
-    }
-}
-
-platform arm {
+# Ensure port can still be parsed on unsupported archs
+set chrome_arch invalid
+platform darwin arm {
     set chrome_arch mac-arm64
 }
-platform i386 {
+platform darwin i386 {
     set chrome_arch mac-x64
 }