Fix highlighting for matchit namespaces with french quotes.

Really this test isn't sufficient because the issue was only
highlighting, not which line we'd jump to, but we can come back and beef
up the test.

ftplugin/lean/lean.lua

@@ -24,7 +24,7 @@ if vim.g.loaded_matchit and not vim.b.match_words then
   vim.b.match_ignorecase = 0
   vim.b.match_words = vim
     .iter({
-      [[\<\%(namespace\|section\)\s\+\(.\{-}\)\>:\<end\s\+\1\>]],
+      [[\<\%(namespace\|section\)\s\+\([^«»]\{-}\>\|«.\{-}»\):\<end\s\+\1]],
       [[^\s*section\s*$:^end\s*$]],
       [[\<if\>:\<then\>:\<else\>]],
     })

spec/matchit_spec.lua

@@ -66,6 +66,29 @@ describe('matchit', function()
     )
   )
 
+  it(
+    'jumps between namespaces named with french quote names',
+    helpers.clean_buffer(
+      [[
+        namespace «1.2»
+
+        section bar
+
+        def f := 37
+
+        end bar
+
+        end «1.2»
+      ]],
+      function()
+        vim.cmd.normal 'gg'
+        assert.current_line.is 'namespace «1.2»'
+        vim.cmd.normal '%'
+        assert.current_line.is 'end «1.2»'
+      end
+    )
+  )
+
   it(
     'jumps between if/then/else',
     helpers.clean_buffer(