Fix ConnecitonPool deadlocking after reaching the connection limit

The issue was with ConcurrentLimiter not decrementing counters on
overload. It was fixed in the latest commit, but concurrentlimiter
version wasn't updated in Pleroma for some reason.

Closes #1977
15 jobs for fix/gun-limiter in 26 minutes and 40 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
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  Test
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  Benchmark
manual #140736
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  Deploy
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manual #140738
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