go.mod: remove exclude rules

go.mod: remove exclude rules

Commit 00a11e91d38b5a1e3540382eaedfda878b1314b1 added these exclude
rules as a temporary workaround until these transitive dependency
versions would be gone;

> downgrade go-difflib and go-spew to tagged releases
>
> These dependencies were updated to "master" in some modules we depend on,
> but have no code-changes since their last release. Unfortunately, this also
> causes a ripple effect, forcing all users of the containerd module to also
> update these dependencies to an unrelease / un-tagged version.
>
> Both these dependencies will unlikely do a new release in the near future,
> so exclude these versions so that we can downgrade to the current release.

Commit fb8c01ded46d2cdbb99720ed33a9f7eb6dc13dda updated the containerd/zfs
module to v2.0.0, which was the remaining dependency using these untagged
versions, so we can remove these exclude rules again.

This reverts commit 00a11e91d38b5a1e3540382eaedfda878b1314b1.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>