A couple of small fixes:

1. remove visionos 1 from @available list as it is behind #if TARGET_OS_VISION check and 1 is the base version.
2. use IPHONEOS_DEPLOYMENT_TARGET env var to generate info.plist for dynamic library with correct properties.

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• The PR is proposed to the proper branch
• There is a reference to the original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake