Update phpspec/prophecy from 1.8.1 to 1.9.0

[violinist-bot]

If you have a high test coverage index, and your tests for this pull request are passing, it should be both safe and recommended to merge this update.

Here is a list of changes between the version you use, and the version this pull request updates to:

• f6811d9 Update changeling for 1.9.0
• 33b058f Merge pull request #435 from tkotosz/feature/add-will-yield-to-method-prophecy
• 9687f4e Merge pull request #429 from timoschinkel/issue-428
• c548392 Merge pull request #422 from ricpelo/patch-1
• bcdce71 Merge pull request #443 from webimpress/hotfix/remove-unused-private-method
• 162aea3 Remove unused private method
• ff58635 Add willYield functionality to MethodProphecy
• 93d6a38 Merge pull request #440 from theodorejb/fix-build
• 3ba8e15 Fix broken build for PHP 5.4 and PHP 5.5
• f7b200e Merge pull request #423 from samnela/patch-1
• 37099f2 Merge pull request #425 from lyrixx/patch-1
• 40c22e8 Merge pull request #434 from tkotosz/misc/fix-specs
• dcf5389 Merge pull request #432 from smoench/fix-compatibility-with-php74
• 8e0f3a0 Fix specs for MethodProphecy
• 7223e88 [README] explain how to return different values for the same call
• 4ab322a fix compatibility with PHP 7.4
• 6e23e4c Allow MethodProphecy::willThrow() to accept Throwable as string
• 55d8139 Update suggested unit test
• 9471613 Bump phpdocumentor/reflection-docblock to ^5.0

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