Fix typo in error code for duplicate entry

[codecov-commenter]

Codecov Report

Patch and project coverage have no change.

Comparison is base (15d3ac9) 78.45% compared to head (750a798) 78.45%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #165 +/- ## ======================================= Coverage 78.45% 78.45% ======================================= Files 17 17 Lines 4373 4373 Branches 987 987 ======================================= Hits 3431 3431 + Misses 711 710 -1 - Partials 231 232 +1 ``` | [Impacted Files](https://app.codecov.io/gh/aiven/myhoard/pull/165?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiven) | Coverage Δ | | |---|---|---| | [myhoard/restore\_coordinator.py](https://app.codecov.io/gh/aiven/myhoard/pull/165?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiven#diff-bXlob2FyZC9yZXN0b3JlX2Nvb3JkaW5hdG9yLnB5) | `78.30% <0.00%> (ø)` | | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/aiven/myhoard/pull/165/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiven)

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.