chore(neptune): update CDK CLI version in deployspec to latest

Update the deployspec.yaml to use latest CDK CLI version to match
the upgraded CDK library (2.236.0) which requires cloud assembly
schema version 48.0.0.

Author: weklund

modules/database/neptune/deployspec.yaml

@@ -3,7 +3,7 @@ deploy:
   phases:
     install:
       commands:
-      - npm install -g aws-cdk@2.147.3
+      - npm install -g aws-cdk@latest
       - pip install -r requirements.txt
     build:
       commands:
@@ -14,7 +14,7 @@ destroy:
   phases:
     install:
       commands:
-      - npm install -g aws-cdk@2.147.3
+      - npm install -g aws-cdk@latest
       - pip install -r requirements.txt
     build:
       commands: