chore(deps): pin dependencies

Change-Id: I46c8f8210471ec0dd46c0ca5d6cfebc0c9008cba
diff --git a/Dockerfile b/Dockerfile
index 7f3d694..43a3841 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM php:8.1-apache
+FROM php:8.1-apache@sha256:e20df709ac9611fde1447de4b56c169520e275d9fca3da0faf9f109e8d0c5b3f
 RUN docker-php-ext-install mysqli
 RUN docker-php-ext-enable mysqli
 RUN mkdir -p /var/phpsessions && chown www-data /var/phpsessions
diff --git a/docker-compose.sample.yml b/docker-compose.sample.yml
index 64e090a..cdf85a0 100644
--- a/docker-compose.sample.yml
+++ b/docker-compose.sample.yml
@@ -14,7 +14,7 @@
       - phpsessions:/var/phpsessions
     restart: unless-stopped
   db:
-    image: mariadb
+    image: mariadb@sha256:9da6213d1a5714c4585c9c0003c51510b320d6f60e53d78701fe1e194126249f
     environment:
       MYSQL_ALLOW_EMPTY_PASSWORD: "yes"
       MARIADB_DATABASE: ${DB_NAME}