chore: bump mockall from 0.14.0 to 0.15.0 (#3744)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Cargo.lock

@@ -181,7 +181,7 @@ lru = "0.18.0"
 # binary mappings into emitted pprof profiles so `pprof` can symbolicate
 # addresses through ASLR.
 mappings = "0.5"
-mockall = "0.14.0"
+mockall = "0.15.0"
 named-lock = "0.4.1"
 near-abi = "0.4.4"
 near-account-id = "2.6.0"