Make CPU percentage test assertion inclusive

We observed in the pipeline this failure:
```
• Failure [1.275 seconds]
SigarShared
/tmp/build/1944c6a2/gopath/src/github.com/cloudfoundry/gosigar/sigar_shared_test.go:14
  ProcCpu
  /tmp/build/1944c6a2/gopath/src/github.com/cloudfoundry/gosigar/sigar_shared_test.go:15
    calculates percentage [It]
    /tmp/build/1944c6a2/gopath/src/github.com/cloudfoundry/gosigar/sigar_shared_test.go:44

    Expected
        <float64>: 1.1
    to be ~
        <float64>: 1

    /tmp/build/1944c6a2/gopath/src/github.com/cloudfoundry/gosigar/sigar_shared_test.go:51
```

This test depends on an actual CPU being stressed by infinitely
calculating the fibonacci sequence.  We suspsect that due to the
variability of the containers in the pipeline, occasionally the
assertion would be barely out of bounds.

Previously, the assertion checked for CPU percentage values from 0.9 -
1.1, exclusive.  We changed this to be inclusive.

Co-authored-by: Chris Selzo <cselzo@vmware.com>
Co-authored-by: Daniel Felipe Ochoa <danielfelipo@vmware.com>

sigar_shared_test.go

@@ -48,7 +48,8 @@ var _ = Describe("SigarShared", func() {
 
 			err := pCpu.Get(cpuGenerator.Process.Pid)
 			Expect(err).ToNot(HaveOccurred())
-			Expect(pCpu.Percent).To(BeNumerically("~", 1.0, 0.1))
+			Expect(pCpu.Percent).To(BeNumerically(">=", 0.9))
+			Expect(pCpu.Percent).To(BeNumerically("<=", 1.1))
 		})
 
 		It("does not conflate multiple processes", func() {