Update operations fail because fields cannot be set

[justaugustus]

From testing in #28 (comment), following the merge of #27:

INFO[0005] updating issue 10066                          app=issue-sync
DEBU[0005] Updating JIRA OSPO-67 with GitHub #28         app=issue-sync
DEBU[0005] Comparing GitHub issue #28 and JIRA issue OSPO-67  app=issue-sync
DEBU[0005] Issues have any differences: true             app=issue-sync
ERRO[0005] Error performing operation; retrying in 552ms: customfield_10025 - Field 'customfield_10025' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0006] Error performing operation; retrying in 1.08s: customfield_10030 - Field 'customfield_10030' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0007] Error performing operation; retrying in 1.31s: customfield_10003 - Field 'customfield_10003' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0008] Error performing operation; retrying in 1.582s: customfield_10027 - Field 'customfield_10027' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0010] Error performing operation; retrying in 2.34s: security - Field 'security' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0013] Error performing operation; retrying in 4.506s: customfield_10005 - Field 'customfield_10005' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0017] Error performing operation; retrying in 3.221s: customfield_10034 - Field 'customfield_10034' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0021] Error performing operation; retrying in 5.608s: votes - Field 'votes' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0027] Error performing operation; retrying in 7.649s: customfield_10029 - Field 'customfield_10029' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0035] Error performing operation; retrying in 15.394s: customfield_10007 - Field 'customfield_10007' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0050] Error updating JIRA issue OSPO-67: backoff error: statuscategorychangedate - Field 'statuscategorychangedate' cannot be set. It is not on the appropriate screen, or unknown.: request failed. Please analyze the request body for more details. Status code: 400  app=issue-sync
ERRO[0050] Error occurred trying to read error body: http2: response body closed  app=issue-sync
ERRO[0050] Error updating issue OSPO-67. Error: updating Jira issue: reading error body: http2: response body closed  app=issue-sync