v1.8.0 bump

[rvagg]

Justification for the semver-minor bump:

• files returned from unixfsnode should be traversable to their substrate #67
• Go 1.20 update (strictly speaking this should be a semver-major but I don't think that's common practice since semver-major bumps are so painful in Go)

[github-actions]

Suggested version: v1.8.0

Comparing to: v1.7.4 (diff)

Changes in go.mod file(s):

diff --git a/go.mod b/go.mod
index c31842f..4e23651 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/ipfs/go-unixfsnode
 
-go 1.19
+go 1.20
 
 require (
 	github.com/ipfs/go-bitfield v1.1.0

gorelease says:

# diagnostics
go.sum: one or more sums are missing. Run 'go mod tidy' to add missing sums.

# summary
Suggested version: v1.8.0

gocompat says:

Your branch is up to date with 'origin/main'.

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