Update dependecies

[nWacky]

• Use image: ^3.2.0, flutter: ">=2.8.0"
• Changed example to use flutter
• Fixed out of bounds error with non square images

[risingwolf21]

Great work. Will merge when you finished that one comment.

[nWacky]

Thank you.

Sorry, I cannot see any comments. Which one?

[risingwolf21]

In lib/edge_detection.dart line 47. Maybe we should use something like min(matrixXLen, matrixYLen) or we encounter the same out of bound error you mentioned. Am I right?