fix(release): allow null values in schema of dockerVersion (#34171)

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## Current Behavior
<!-- This is the behavior we have today -->

TS file documents `projectVersionData.dockerVersion` as having type
`string | undefined`. However, code behaves differently. For instance,
[here](https://github.com/nrwl/nx/blob/e57848cea748b85f17e5fc704b901975a8424c4d/packages/nx/src/command-line/release/version/release-group-processor.ts#L128)
and
[here](https://github.com/nrwl/nx/blob/e57848cea748b85f17e5fc704b901975a8424c4d/packages/nx/src/command-line/release/utils/shared.ts#L294)
it is setting as and comparing against `null`.

## Expected Behavior
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-->

Schema has value that code sets (`null`)

## Related Issue(s)
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merged. -->

Fixes #34172

(cherry picked from commit b72a203)

Author: mpsanchis

packages/nx/src/command-line/release/utils/shared.ts

@@ -34,7 +34,7 @@ export interface VersionDataEntry {
    * dockerVersion will be populated if the project is a docker project and has been
    * included within this release.
    */
-  dockerVersion?: string;
+  dockerVersion?: string | null;
   /**
    * The list of projects which depend upon the current project.
    */