Shards: Add required dependencies and update lock file

shard.lock

@@ -32,6 +32,10 @@ shards:
     git: https://github.com/will/crystal-pg.git
     version: 0.24.0
 
+  pool:
+    git: https://github.com/ysbaddaden/pool.git
+    version: 0.2.4
+
   protodec:
     git: https://github.com/iv-org/protodec.git
     version: 0.1.5
@@ -40,6 +44,10 @@ shards:
     git: https://github.com/luislavena/radix.git
     version: 0.4.1
 
+  redis:
+    git: https://github.com/stefanwille/crystal-redis.git
+    version: 2.8.3
+
   spectator:
     git: https://github.com/icy-arctic-fox/spectator.git
     version: 0.10.4

shard.yml

@@ -10,27 +10,38 @@ targets:
     main: src/invidious.cr
 
 dependencies:
+  # Database
   pg:
     github: will/crystal-pg
     version: ~> 0.24.0
   sqlite3:
     github: crystal-lang/crystal-sqlite3
     version: ~> 0.18.0
+
+  # Web server
   kemal:
     github: kemalcr/kemal
     version: ~> 1.1.2
   kilt:
     github: jeromegn/kilt
     version: ~> 0.6.1
+  athena-negotiation:
+    github: athena-framework/negotiation
+    version: ~> 0.1.1
+
+  # Youtube backend
   protodec:
     github: iv-org/protodec
     version: ~> 0.1.5
   lsquic:
     github: iv-org/lsquic.cr
     version: ~> 2.18.1-2
-  athena-negotiation:
-    github: athena-framework/negotiation
-    version: ~> 0.1.1
+
+  # Caching
+  redis:
+    github: stefanwille/crystal-redis
+    version: ~> 2.8.3
+
 
 development_dependencies:
   spectator: