0.13: [Bug]: exec#env values are being validated as "string" required instead of "primitive" required

[jamesylgan]

Garden Bonsai (0.13) Bug

https://docs.garden.io/reference/module-types/exec#env indicates that the exec#env map should accept primitives. We previously had a boolean value, and validation forced us to change it to string type

Current Behavior

Error validating spec for Run type=exec name=********* (from module *********) (garden-base/dependencies/*********): [
{
  "code": "invalid_type",
  "expected": "string",
  "received": "boolean",
  "path": [
    "env",
    "*********"
  ],
  "message": "Expected string, received boolean"
}
]

Expected behavior

No validation occurs because booleans are an acceptable type for exec#env