Security updates 8.6.3 - System.Security.Cryptography.Xml (#2438)

* Added DisableImageFunctionDownloads property to ParsingConfiguration. If true the IMAGE function will not download external content

* Update System.Security.Cryptography.Xml to 8.0.4/9.0.18/10.0.10 for CVE-2026-47302/47304/50525/50527/50648. Bump version to 8.6.3.

* Additional fixes för appveyor8.yml, fixedIssures.md and EPPlus project file

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Co-authored-by: swmal <{ID}+username}@users.noreply.github.com>

Updated version number on EPPlus.Interfaces and EPPlus.System.Drawing…

… projects

Fixed small error in positioning of shapes in charts

EPPlus version 8.6.0

EPPlus version 8.5.4

EPPlus version 8.5.3

Set Ignore attribute on Groupby Tests

Adjusted release date in project readme

EPPlus version 8.5.0

EPPlus version 8.4.2