fix(bot): install libgssapi-krb5-2 in runtime image

Telegram bot's long-polling hangs after the first GetUpdates request
because libgssapi-krb5.so.2 is missing from the runtime-deps:10.0-noble
final image. .NET runtime attempts dlopen() of libgssapi during the
HTTPS handshake; without the library the HttpClient connection pool
enters an unrecoverable state and TelegramBotService never receives
new updates, even though SessionSchedulerService keeps sending
outgoing messages successfully.

Symptom (Loki, container gmrelaybot-bot-1):
  Telegram bot polling started
  Polling error, retrying in 5s
  Telegram.Bot.Exceptions.RequestException: Bot API Service Failure
  Cannot load library libgssapi_krb5.so.2

After the single Polling error, no Error handling update, no further
Polling error, and getUpdates from outside returns [] forever.

Fix: install libgssapi-krb5-2 alongside wget in the final stage of
src/GmRelay.Bot/Dockerfile. This also future-proofs Npgsql GSS/SSPI
Kerberos authentication for PostgreSQL.

Closes #129.

Bump version 3.9.5 -> 3.9.6

compose.yaml

@@ -49,7 +49,7 @@ services:
         crond -f
 
   bot:
-    image: git.codeanddice.ru/toutsu/gmrelay-bot:3.9.5
+    image: git.codeanddice.ru/toutsu/gmrelay-bot:3.9.6
     restart: always
     depends_on:
       db:
@@ -67,7 +67,7 @@ services:
       retries: 3
 
   discord:
-    image: git.codeanddice.ru/toutsu/gmrelay-discord-bot:3.9.5
+    image: git.codeanddice.ru/toutsu/gmrelay-discord-bot:3.9.6
     restart: always
     depends_on:
       db:
@@ -86,7 +86,7 @@ services:
       retries: 3
 
   web:
-    image: git.codeanddice.ru/toutsu/gmrelay-web:3.9.5
+    image: git.codeanddice.ru/toutsu/gmrelay-web:3.9.6
     restart: always
     depends_on:
       db: