Fixed typos

Author: GrahamCampbell

src/Api/Issues.php

@@ -399,7 +399,7 @@ public function closedByMergeRequests($project_id, int $issue_iid)
      */
     public function relatedMergeRequests($project_id, int $issue_iid)
     {
-        return $this->get($this->getProjectPath($project_id, 'issues/'.$this::encodePath($issue_iid).'/related_merge_requests'));
+        return $this->get($this->getProjectPath($project_id, 'issues/'.self::encodePath($issue_iid).'/related_merge_requests'));
     }
 
     /**

src/Api/Projects.php

@@ -530,7 +530,7 @@ public function boards($project_id)
      */
     public function getRepositoryCommitDiscussions($project_id, string $commit_id)
     {
-        return $this->get($this->getProjectPath($project_id, 'repository/commits/'.$this::encodePath($commit_id)).'/discussions');
+        return $this->get($this->getProjectPath($project_id, 'repository/commits/'.self::encodePath($commit_id)).'/discussions');
     }
 
     /**