Fix Dockerfile deprecated syntax.

```
 1 warning found (use docker --debug to expand):
 - LegacyKeyValueFormat: "ENV key=value" should be used instead of legacy "ENV key value" format (line 48)
```

Signed-off-by: Brian Fletcher <brian@roadie.io>

.changeset/shaggy-weeks-hunt.md

@@ -0,0 +1,5 @@
+---
+'@backstage/create-app': patch
+---
+
+Tweak `Dockerfile` to fix deprecated syntax.

docs/deployment/docker.md

@@ -90,7 +90,7 @@ COPY --chown=node:node .yarnrc.yml ./
 ENV NODE_ENV=production
 
 # This disables node snapshot for Node 20 to work with the Scaffolder
-ENV NODE_OPTIONS "--no-node-snapshot"
+ENV NODE_OPTIONS="--no-node-snapshot"
 
 # Copy repo skeleton first, to avoid unnecessary docker cache invalidation.
 # The skeleton contains the package.json of each package in the monorepo,
@@ -287,7 +287,7 @@ COPY --chown=node:node examples ./examples
 ENV NODE_ENV=production
 
 # This disables node snapshot for Node 20 to work with the Scaffolder
-ENV NODE_OPTIONS "--no-node-snapshot"
+ENV NODE_OPTIONS="--no-node-snapshot"
 
 CMD ["node", "packages/backend", "--config", "app-config.yaml", "--config", "app-config.production.yaml"]
 ```

packages/create-app/templates/default-app/packages/backend/Dockerfile

@@ -45,7 +45,7 @@ COPY --chown=node:node .yarnrc.yml ./
 ENV NODE_ENV=production
 
 # This disables node snapshot for Node 20 to work with the Scaffolder
-ENV NODE_OPTIONS "--no-node-snapshot"
+ENV NODE_OPTIONS="--no-node-snapshot"
 
 # Copy repo skeleton first, to avoid unnecessary docker cache invalidation.
 # The skeleton contains the package.json of each package in the monorepo,