deps: Add csslib as a direct dependency

It will be used in later commits to parse inline CSS styles
in HTML while parsing KaTeX HTML spans.

Author: rajveermalviya

pubspec.lock

@@ -227,7 +227,7 @@ packages:
     source: hosted
     version: "3.0.6"
   csslib:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: csslib
       sha256: "09bad715f418841f976c77db72d5398dc1253c21fb9c0c7f0b0b985860b2d58e"

pubspec.yaml

@@ -39,6 +39,7 @@ dependencies:
   collection: ^1.17.2
   convert: ^3.1.1
   crypto: ^3.0.3
+  csslib: ^1.0.2
   device_info_plus: ^11.2.0
   drift: ^2.23.0
   file_picker: ^9.0.2