support using M: a as b correctly

JuliaLang/julia#37396 added support for this
syntax as well, but CSTParser currently returns an error token.

Author: simeonschaub

src/components/keywords.jl

@@ -173,12 +173,12 @@ function parse_imports(ps::ParseState)
     elseif iscolon(ps.nt)
         ret = EXPR(kwt, EXPR[EXPR(EXPR(:OPERATOR, next(ps)), EXPR[arg])], EXPR[kw])
 
-        arg = parse_dot_mod(ps, true, allow_as)
+        arg = parse_dot_mod(ps, true, true)
         push!(ret.args[1], arg)
         prevpos = position(ps)
         while iscomma(ps.nt)
             pushtotrivia!(ret.args[1], accept_comma(ps))
-            arg = parse_dot_mod(ps, true, allow_as)
+            arg = parse_dot_mod(ps, true, true)
             push!(ret.args[1], arg)
             prevpos = loop_check(ps, prevpos)
         end

test/parser.jl

@@ -899,7 +899,11 @@ end""" |> test_expr
         @testset "import .. as .. syntax" begin
             @test test_expr("import a as b")
             @test test_expr("import a as b, c")
+            @test test_expr("import M: a as b")
+            @test test_expr("import M: a as b, c")
             @test CSTParser.parse("using a as b")[2].head === :errortoken
+            @test test_expr("using M: a as b")
+            @test test_expr("using M: a as b, c")
         end
     end
     @testset "exor #201" begin