Migrate from pedantic to lints (dart-lang/markdown#370)

diff --git a/pkgs/markdown/analysis_options.yaml b/pkgs/markdown/analysis_options.yaml
index 755e1a2..2f0f043 100644
--- a/pkgs/markdown/analysis_options.yaml
+++ b/pkgs/markdown/analysis_options.yaml
@@ -1,4 +1,4 @@
-include: package:pedantic/analysis_options.1.11.0.yaml
+include: package:lints/recommended.yaml
 analyzer:
   language:
     strict-inference: true
diff --git a/pkgs/markdown/lib/src/ast.dart b/pkgs/markdown/lib/src/ast.dart
index 8488a44..25b675b 100644
--- a/pkgs/markdown/lib/src/ast.dart
+++ b/pkgs/markdown/lib/src/ast.dart
@@ -85,7 +85,7 @@
   UnparsedContent(this.textContent);
 
   @override
-  void accept(NodeVisitor visitor) => null;
+  void accept(NodeVisitor visitor) {}
 }
 
 /// Visitor pattern for the AST.
diff --git a/pkgs/markdown/pubspec.yaml b/pkgs/markdown/pubspec.yaml
index aac2de4..4f55179 100644
--- a/pkgs/markdown/pubspec.yaml
+++ b/pkgs/markdown/pubspec.yaml
@@ -24,7 +24,7 @@
   html: ^0.15.0-nullsafety
   io: ^1.0.0
   js: ^0.6.3
+  lints: ^1.0.1
   path: ^1.8.0
-  pedantic: ^1.11.0
   test: ^1.16.0
   yaml: ^3.0.0
diff --git a/pkgs/markdown/tool/README.md b/pkgs/markdown/tool/README.md
index 724ae1e..ff2f749 100644
--- a/pkgs/markdown/tool/README.md
+++ b/pkgs/markdown/tool/README.md
@@ -2,7 +2,7 @@
 
 This directory contains tools for developers of the Dart markdown package.
 
-## dartdoc-compare.dart
+## dartdoc_compare.dart
 
 When you make a change to the package that might have subtle consequences on
 how Markdown is parsed, it would be really great to see how your output compares
@@ -10,15 +10,15 @@
 
 One such collection is the Dartdoc comments of any Dart package, which [dartdoc]
 translates into HTML, with the help of this markdown package. You can use the
-`dartdoc-compare.dart` script to compare what changes your code will make to
+`dartdoc_compare.dart` script to compare what changes your code will make to
 dartdoc's output. Here's how it works:
 
 1. Clone the [dartdoc git repository].
 2. Get a copy of some Dart code that you would like to use for the comparison.
-3. Run the `dartdoc-compare.dart` script like so:
+3. Run the `dartdoc_compare.dart` script like so:
 
    ```
-   $ dart tool/dartdoc-compare.dart \
+   $ dart tool/dartdoc_compare.dart \
          --dartdoc-dir=<dartdoc repo> \
          --before=<git SHA of "previous" code> \
          <directory of dart code for comparison>
diff --git a/pkgs/markdown/tool/dartdoc-compare.dart b/pkgs/markdown/tool/dartdoc_compare.dart
similarity index 98%
rename from pkgs/markdown/tool/dartdoc-compare.dart
rename to pkgs/markdown/tool/dartdoc_compare.dart
index 052ca5e..7c24553 100644
--- a/pkgs/markdown/tool/dartdoc-compare.dart
+++ b/pkgs/markdown/tool/dartdoc_compare.dart
@@ -108,7 +108,7 @@
       var out = Directory.systemTemp
           .createTempSync('dartdoc-compare-${markdownRef}__');
       var cmd = 'dart';
-      var args = ['$dartdocBin', '--output=${out.path}'];
+      var args = [dartdocBin, '--output=${out.path}'];
 
       if (sdk) {
         args.add('--sdk-docs');