go.mod: Bump hcsshim to v0.9.1

This tag contains some changes for the Windows shim for retrying
stdio named pipe connections if containerd restarts. It also is built with v1.1.0 of
ttrpc which has some fixes for a deadlock we'd observed on Windows.

Signed-off-by: Daniel Canter <dcanter@microsoft.com>

integration/client/go.mod

@@ -3,7 +3,7 @@ module github.com/containerd/containerd/integration/client
 go 1.15
 
 require (
-	github.com/Microsoft/hcsshim v0.9.0
+	github.com/Microsoft/hcsshim v0.9.1
 	github.com/Microsoft/hcsshim/test v0.0.0-20210408205431-da33ecd607e1
 	github.com/containerd/cgroups v1.0.2
 	// the actual version of containerd is replaced with the code at the root of this repository

integration/client/go.sum

@@ -48,8 +48,8 @@ github.com/Microsoft/go-winio v0.5.0/go.mod h1:JPGBdM1cNvN/6ISo+n8V5iA4v8pBzdOpz
 github.com/Microsoft/hcsshim v0.8.15/go.mod h1:x38A4YbHbdxJtc0sF6oIz+RG0npwSCAvn69iY6URG00=
 github.com/Microsoft/hcsshim v0.8.16/go.mod h1:o5/SZqmR7x9JNKsW3pu+nqHm0MF8vbA+VxGOoXdC600=
 github.com/Microsoft/hcsshim v0.8.20/go.mod h1:+w2gRZ5ReXQhFOrvSQeNfhrYB/dg3oDwTOcER2fw4I4=
-github.com/Microsoft/hcsshim v0.9.0 h1:BBgYMxl5YZDZVIijz02AlDINpYZOzQqRNCl9CZM13vk=
-github.com/Microsoft/hcsshim v0.9.0/go.mod h1:VBJWdC71NSWPlEo7lwde1aL21748J8B6Sdgno7NqEGE=
+github.com/Microsoft/hcsshim v0.9.1 h1:VfDCj+QnY19ktX5TsH22JHcjaZ05RWQiwDbOyEg5ziM=
+github.com/Microsoft/hcsshim v0.9.1/go.mod h1:Y/0uV2jUab5kBI7SQgl62at0AVX7uaruzADAVmxm3eM=
 github.com/Microsoft/hcsshim/test v0.0.0-20210408205431-da33ecd607e1 h1:pVKfKyPkXna29XlGjxSr9J0A7vNucOUHZ/2ClcTWalw=
 github.com/Microsoft/hcsshim/test v0.0.0-20210408205431-da33ecd607e1/go.mod h1:Cmvnhlie15Ha2UYrJs9EhgSx76Bq9RV2FgfEiT78GhI=
 github.com/NYTimes/gziphandler v0.0.0-20170623195520-56545f4a5d46/go.mod h1:3wb06e3pkSAbeQ52E9H9iFoQsEEwGN64994WTCIhntQ=