[OOB] Upgrades 'flex' to '1.4.0'

[SvcGitHubPATagentoperatorimages]

Automated OOB update requested by SvcGitHubPATagentoperatorimages.

Agent: flex
Version: 1.3.0 -> 1.4.0

[github-actions]

Images built:

dotnet-core: ghcr.io/contrast-security-oss/agent-operator-images/agent-dotnet-core@sha256:f347b908df2a28ed64ec2c8d63139e0b76694d6947588c84f167a80a8fb6bc92
dotnet-framework: ghcr.io/contrast-security-oss/agent-operator-images/agent-dotnet-framework@sha256:9f6f484d7a17c98d20a81593dfbf26a54eebbaf85bd2642f08c1e6ed2c77aecf
java: ghcr.io/contrast-security-oss/agent-operator-images/agent-java@sha256:c19423e1ffda1c91e13aa8764112f5261059bd92012c55c2b7d199e5b52e264a
nodejs: ghcr.io/contrast-security-oss/agent-operator-images/agent-nodejs@sha256:5585f0b06918e3965468bfb391f2c89d7ebe63f2ceeb50dfe953490b11f18959
php: ghcr.io/contrast-security-oss/agent-operator-images/agent-php@sha256:f0a27c01c237aa4f3d994efb7b09851d92a9e20f79408d4665a58269c001ee84
python: ghcr.io/contrast-security-oss/agent-operator-images/agent-python@sha256:e977dfd3d13917743149aadcd69963ed90b48c4739f0c43663160afd654ae690
flex: ghcr.io/contrast-security-oss/agent-operator-images/agent-flex@sha256:f8d8bd396aa1ba2d74112210498e369c87d9d1856710bc3e5112bdd1a54bd8cc