Remove no longer supported dependabot commands

Fixes dependabot/dependabot-core#14075 (comment)

Author: jfrost-mo

content/code-security/reference/supply-chain-security/dependabot-pull-request-comment-commands.md

@@ -20,18 +20,13 @@ You can use any of the following commands on a {% data variables.product.prodnam
 
 | Command                                      | Description                                                                                                                                                                                                                     |
 | --- | --- |
-| `@dependabot cancel merge`                   | Cancels a previously requested merge.                                                                                                                                                                                          |
-| `@dependabot close`                          | Closes the pull request and prevents {% data variables.product.prodname_dependabot %} from recreating that pull request. You can achieve the same result by closing the pull request manually.                                  |
 | `@dependabot ignore this dependency`         | Closes the pull request and prevents {% data variables.product.prodname_dependabot %} from creating any more pull requests for this dependency (unless you reopen the pull request or upgrade to the suggested version yourself). |
 | `@dependabot ignore this major version`      | Closes the pull request and prevents {% data variables.product.prodname_dependabot %} from creating any more pull requests for this major version (unless you reopen the pull request or upgrade to this major version yourself). |
 | `@dependabot ignore this minor version`      | Closes the pull request and prevents {% data variables.product.prodname_dependabot %} from creating any more pull requests for this minor version (unless you reopen the pull request or upgrade to this minor version yourself). |
 | `@dependabot ignore this patch version`      | Closes the pull request and prevents {% data variables.product.prodname_dependabot %} from creating any more pull requests for this patch version (unless you reopen the pull request or upgrade to this patch version yourself). |
-| `@dependabot merge`                          | Merges the pull request once your CI tests have passed.                                                                                                                                                                        |
 | `@dependabot rebase`                         | Rebases the pull request.                                                                                                                                                                                                      |
 | `@dependabot recreate`                       | Recreates the pull request, overwriting any edits that have been made to the pull request.                                                                                                                                     |
-| `@dependabot reopen`                         | Reopens the pull request if the pull request is closed.                                                                                                                                                                        |
 | `@dependabot show DEPENDENCY_NAME ignore conditions` | Retrieves information on the ignore conditions for the specified dependency, and comments on the pull request with a table that displays all ignore conditions for the dependency. For example, `@dependabot show express ignore conditions` would find all `ignore` conditions stored for the Express dependency, and comment on the pull request with that information. |
-| `@dependabot squash and merge`               | Squashes and merges the pull request once your CI tests have passed.                                                                                                                                                           |
 
 ## Commands for grouped version updates