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

Author: renovate[bot]

Gemfile.lock

@@ -1,22 +1,31 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    base64 (0.3.0)
     json (2.7.1)
-    mustermann (3.0.0)
+    logger (1.7.0)
+    mustermann (3.0.4)
       ruby2_keywords (~> 0.0.1)
     nio4r (2.7.0)
     puma (6.4.0)
       nio4r (~> 2.0)
-    rack (2.2.8)
-    rack-protection (3.1.0)
-      rack (~> 2.2, >= 2.2.4)
+    rack (3.2.0)
+    rack-protection (4.1.1)
+      base64 (>= 0.1.0)
+      logger (>= 1.6.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.1.1)
+      base64 (>= 0.1.0)
+      rack (>= 3.0.0)
     ruby2_keywords (0.0.5)
-    sinatra (3.1.0)
+    sinatra (4.1.1)
+      logger (>= 1.6.0)
       mustermann (~> 3.0)
-      rack (~> 2.2, >= 2.2.4)
-      rack-protection (= 3.1.0)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.1.1)
+      rack-session (>= 2.0.0, < 3)
       tilt (~> 2.0)
-    tilt (2.3.0)
+    tilt (2.6.1)
 
 PLATFORMS
   ruby