[share_plus_ios] fix sharing malformed urls

[alexbatalov]

Description

Fixes #531

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Breaking Change

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[miquelbeltran]

Very nice, thanks! Can you add a new line on the CHANGELOG and the pubspec.yaml plugin version? as explained in the contribution guide.

[miquelbeltran]

Can you pull the changes from main? there was a release meanwhile.

[alexbatalov]

sorry for having force-pushed, have to clean up email mess in earlier commits

[miquelbeltran]

thank you!