monaco_editor: fix offset in pylint diagnostics

when fixing coding style in 0b8b8475 (administration,core: wrong
location when reporting pylint errors, 2024-05-25) it became wrong here.
20 jobs for for_testrunner_1 in 0 seconds
latest
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

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passed ERP5.CodingStyleTest-TestRunner1

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failed ERP5.PerformanceTest-Master

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failed ERP5.PerformanceTest-TestRunner1

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failed ERP5.UnitTest-Master

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passed ERP5.UnitTest-TestRunner1

04:03:13

passed SlapOS.Eggs.UnitTest-Master.Python2

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passed SlapOS.Eggs.UnitTest-Master.Python3

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passed Wendelin.UnitTest-Master

00:47:30

passed ERP5.CodingStyleTest-TestRunner1

07:22:14

passed ERP5.CodingStyleTest-TestRunner1

11:56:59

passed ERP5.CodingStyleTest-TestRunner1

00:54:38

failed ERP5.PerformanceTest-TestRunner1

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failed ERP5.PerformanceTest-TestRunner1

04:08:21

failed ERP5.PerformanceTest-TestRunner1

00:42:43

failed ERP5.UnitTest-TestRunner1

03:10:09

passed ERP5.UnitTest-TestRunner1

14:35:37

passed ERP5.UnitTest-TestRunner1

02:21:24

passed ERP5.UnitTest-TestRunner1

06:52:55

failed ERP5.UnitTest-TestRunner1

01:33:24