core_text: drop dependency on PyXML

use sax.xml API which gives us the first parser available, instead of
using a specific parser that happens to come from pyxml
27 jobs for fix/sql_browser_bigint in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

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passed ERP5.PerformanceTest-Master

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failed ERP5.UnitTest-Master

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passed SlapOS.Eggs.UnitTest-Master.Python2

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passed SlapOS.Eggs.UnitTest-Master.Python3

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passed ERP5.CodingStyleTest-Master

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passed ERP5.CodingStyleTest-Master

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passed ERP5.CodingStyleTest-Master

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passed ERP5.CodingStyleTest-Master

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passed ERP5.PerformanceTest-Master

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passed ERP5.PerformanceTest-Master

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passed ERP5.PerformanceTest-Master

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passed ERP5.PerformanceTest-Master

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failed ERP5.UnitTest-Master

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failed ERP5.UnitTest-Master

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failed ERP5.UnitTest-Master

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failed ERP5.UnitTest-Master

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passed SlapOS.Eggs.UnitTest-Master.Python2

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passed SlapOS.Eggs.UnitTest-Master.Python2

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passed SlapOS.Eggs.UnitTest-Master.Python2

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passed SlapOS.Eggs.UnitTest-Master.Python2

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passed SlapOS.Eggs.UnitTest-Master.Python2

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passed SlapOS.Eggs.UnitTest-Master.Python3

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passed SlapOS.Eggs.UnitTest-Master.Python3

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passed SlapOS.Eggs.UnitTest-Master.Python3

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passed SlapOS.Eggs.UnitTest-Master.Python3

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passed SlapOS.Eggs.UnitTest-Master.Python3

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