Fix pool flaky test (#950)

### Description
Fix pool flaky test.

### Checklist
- [x] Code compiles correctly
- [x] Code is formatted according to [Coding
Conventions](../blob/master/CodingConventions.md)
- [x] Created tests which fail without the change (if possible)
- [x] All tests passing (`dotnet test`)
- [x] Extended the README / documentation, if necessary
- [ ] Provide JIRA issue id (if possible) or GitHub issue id in PR name

Snowflake.Data.Tests/IntegrationTests/ConnectionMultiplePoolsIT.cs

@@ -195,6 +195,7 @@ public void TestWaitInAQueueForAnIdleSession()
             const long CMaxConnectDuration = AMaxConnectionReleaseTime - CDelay; // 3650 - 800 = 2850
             const long DMinConnectDuration = BMinConnectionReleaseTime - DDelay - StartDelayPessimisticEstimate; // 2400 - 1200 - 350 = 850
             const long DMaxConnectDuration = BMaxConnectionReleaseTime - DDelay; // 3650 - 800 = 2850
+            const long MeasurementTolerance = 25;
 
             var threads = new ConnectingThreads(connectionString)
                 .NewThread("A", ADelay, ABDelayAfterConnect, true)
@@ -223,8 +224,8 @@ public void TestWaitInAQueueForAnIdleSession()
             // first to wait from C and D should first to connect, because we won't create a new session, we just reuse sessions returned by A and B threads
             Assert.AreEqual(waitingEvents[0].ThreadName, lastConnectingEventsGroup[0].ThreadName);
             Assert.AreEqual(waitingEvents[1].ThreadName, lastConnectingEventsGroup[1].ThreadName);
-            Assert.That(lastConnectingEventsGroup[0].Duration, Is.InRange(CMinConnectDuration, CMaxConnectDuration));
-            Assert.That(lastConnectingEventsGroup[1].Duration, Is.InRange(DMinConnectDuration, DMaxConnectDuration));
+            Assert.That(lastConnectingEventsGroup[0].Duration, Is.InRange(CMinConnectDuration - MeasurementTolerance, CMaxConnectDuration));
+            Assert.That(lastConnectingEventsGroup[1].Duration, Is.InRange(DMinConnectDuration - MeasurementTolerance, DMaxConnectDuration));
         }
 
         [Test]