Fix Clippy warning (#718)
Fix Clippy warning (#718)

Rewrite `match` block using `matches` macro as it is now a
recommended way to perform such checks

(cherry picked from commit 2522a5d7ce135ba4ca688687f217ecb349d2a1f7)

Signed-off-by: Alexei Lozovsky <7b9769c9c63db7b456a556857e9f88090ee9c9a2@cossacklabs.com>

cossacklabs/themis,cossacklabs/themis,cossacklabs/themis,cossacklabs/themis,cossacklabs/themis,cossacklabs/themis,cossacklabs/themis,cossacklabs/themis,cossacklabs/themis,cossacklabs/themis,cossacklabs/themis,cossacklabs/themis,cossacklabs/themis