Attempting to create a relationship via API POST to /api/relations endpoint returns an error

[akersj]

If you attempt to create a relationship via API POST to /api/relations with a valid payload the caller is returned 500 Internal Server Error with payload:

{
  "@context": "/api/contexts/Error",
  "@type": "hydra:Error",
  "hydra:title": "An error occurred",
  "hydra:description": "Variable \"‘api\" is not valid around position 12 for expression `is_granted(‘api:post’)`.",
  "trace": [
    {
      "namespace": "",
      "short_class": "",
      "class": "",
      "type": "",
      "function": "",
      "file": "/Users/jamie/Desktop/Hotarucon/vendor/symfony/expression-language/Parser.php",
      "line": 230,
      "args": []
    },

(rest of stack trace removed as it adds little value)

Details

Question	Answer
Relevant Bolt Version	5.1.0
Install type	Composer install
BC Break	n/a
PHP version	7.4
Web server	Apache
For UX/UI issues	n/a

Reproduction

Send a valid POST request to /api/relations using Postman or Bolt's built-in API tools. E.g.

{
  "fromContent": "/api/contents/123",
  "toContent": "/api/contents/116",
  "position": 0
}

Expected result

The caller is returned 200 OK with a payload describing the new relationship.

Actual result

The caller is returned 500 Internal Server Error with a payload including a stack trace.

Potential cause

(My apologies I am a software tester by trade not a developer!)
In /src/Entity/Relation.php on line 18 the wrong quotation marks are used around api:post.

Bug:
* "post"={"security"="is_granted(‘api:post’)"}

Correct:
* "post"={"security"="is_granted('api:post')"}