chore(deps): update dependency sinatra to v4 [security]

Author: renovate[bot]

Gemfile.lock

@@ -13,7 +13,7 @@ GEM
       minitest (>= 5.1)
       securerandom (>= 0.3)
       tzinfo (~> 2.0, >= 2.0.5)
-    base64 (0.2.0)
+    base64 (0.3.0)
     benchmark (0.3.0)
     better_errors (2.10.1)
       erubi (>= 1.0.0)
@@ -60,7 +60,7 @@ GEM
     mini_portile2 (2.8.9)
     minitest (5.25.5)
     multi_json (1.15.0)
-    mustermann (3.0.3)
+    mustermann (3.0.4)
       ruby2_keywords (~> 0.0.1)
     newrelic_rpm (8.16.0)
     nokogiri (1.18.9)
@@ -137,7 +137,7 @@ GEM
       eventmachine (~> 1.0, >= 1.0.4)
       rack (>= 1, < 3)
     thor (1.4.0)
-    tilt (2.6.0)
+    tilt (2.6.1)
     tty-pager (0.14.0)
       strings (~> 0.2.0)
       tty-screen (~> 0.8)