chore: upgrade to Node 18

This was previously blocked by the outdated mock-fs version

docker/Dockerfile.release

@@ -2,7 +2,7 @@
 # Builder image
 # ------------------------------------------------
 
-FROM ghcr.io/thumbsup/build:node-14 as build
+FROM ghcr.io/thumbsup/build:node-18 as build
 
 # Install thumbsup locally
 WORKDIR /thumbsup
@@ -18,7 +18,7 @@ RUN npm install thumbsup@${PACKAGE_VERSION}
 # Runtime image
 # ------------------------------------------------
 
-FROM ghcr.io/thumbsup/runtime:node-14
+FROM ghcr.io/thumbsup/runtime:node-18
 
 # Use tini as an init process
 # to ensure all child processes (ffmpeg...) are always terminated properly

docker/Dockerfile.test

@@ -1,5 +1,5 @@
 # Node.js + build dependencies + runtime dependencies
-FROM ghcr.io/thumbsup/build:node-14
+FROM ghcr.io/thumbsup/build:node-18
 WORKDIR /app
 
 # Switch to a non-root user