Bump imgutil to include off-by-one bounds fix in layout layer facade

Picks up buildpacks/imgutil#308, which fixes an index-out-of-range panic
in the layout layer facade when an OCI layout image's manifest and config
disagree on layer count.

Author: jabrown85

go.mod

@@ -4,7 +4,7 @@ require (
 	github.com/BurntSushi/toml v1.6.0
 	github.com/apex/log v1.9.0
 	github.com/awslabs/amazon-ecr-credential-helper/ecr-login v0.12.0
-	github.com/buildpacks/imgutil v0.0.0-20260415151438-73856e68b72b
+	github.com/buildpacks/imgutil v0.0.0-20260715132717-40ca3490b49e
 	github.com/chrismellard/docker-credential-acr-env v0.0.0-20230304212654-82a0ddb27589
 	github.com/containerd/containerd v1.7.33
 	github.com/docker/docker v28.5.2+incompatible

go.sum

@@ -155,8 +155,8 @@ github.com/breml/bidichk v0.3.3 h1:WSM67ztRusf1sMoqH6/c4OBCUlRVTKq+CbSeo0R17sE=
 github.com/breml/bidichk v0.3.3/go.mod h1:ISbsut8OnjB367j5NseXEGGgO/th206dVa427kR8YTE=
 github.com/breml/errchkjson v0.4.1 h1:keFSS8D7A2T0haP9kzZTi7o26r7kE3vymjZNeNDRDwg=
 github.com/breml/errchkjson v0.4.1/go.mod h1:a23OvR6Qvcl7DG/Z4o0el6BRAjKnaReoPQFciAl9U3s=
-github.com/buildpacks/imgutil v0.0.0-20260415151438-73856e68b72b h1:wW08ZcJrzVhubQjTOkjkWzfeVHAHW0Tlmg3twecDauA=
-github.com/buildpacks/imgutil v0.0.0-20260415151438-73856e68b72b/go.mod h1:EBy9ZOatKkTBAWOgN2Y0aNV4P40dOdGyzzB9q2a5HBE=
+github.com/buildpacks/imgutil v0.0.0-20260715132717-40ca3490b49e h1:mUevA4UuzrnUl/5EiQ1f7DfC9sGdKtFJFzoRYn8Urvk=
+github.com/buildpacks/imgutil v0.0.0-20260715132717-40ca3490b49e/go.mod h1:EBy9ZOatKkTBAWOgN2Y0aNV4P40dOdGyzzB9q2a5HBE=
 github.com/butuzov/ireturn v0.4.0 h1:+s76bF/PfeKEdbG8b54aCocxXmi0wvYdOVsWxVO7n8E=
 github.com/butuzov/ireturn v0.4.0/go.mod h1:ghI0FrCmap8pDWZwfPisFD1vEc56VKH4NpQUxDHta70=
 github.com/butuzov/mirror v1.3.0 h1:HdWCXzmwlQHdVhwvsfBb2Au0r3HyINry3bDWLYXiKoc=