Version 3.0.0

• New #43: Add APCu counters storage (@jiaweipan)
• Chg #21: Update yiisoft/http dependency (@devanych)
• Chg #31: Raise yiisoft/cache dependency version to ^3.0 (@samdark)
• Chg #34: Raise psr/http-message dependency version to ^1.1|^2.0 (@samdark)
• Enh #25: Raise minimum PHP version to 8.0 (@terabytesoftw)
• Enh #26: Add psr/simple-cache dependency version ^3.0 support (@vjik)
• Enh #41: Adapt package to concurrent requests, for this StorageInterface method save() split to
  saveIfNotExists() and saveCompareAndSwap() (@jiaweipan)