internal/encoding/yaml: fix go1.12 breakage

The yaml.v3 package does not seem to support
0oxxx-stly octal numbers.

Change-Id: I8b37cd35139c01d415f5ed3d57bd957bfc342e56
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/5089
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
diff --git a/internal/encoding/yaml/encode_test.go b/internal/encoding/yaml/encode_test.go
index c73a2cc..33d478a 100644
--- a/internal/encoding/yaml/encode_test.go
+++ b/internal/encoding/yaml/encode_test.go
@@ -73,7 +73,6 @@
 		int: 1K
 		bin: 0b11
 		hex: 0x11
-		oct: 0o11
 		dec: .3
 		dat: '\x80'
 		nil: null
@@ -87,7 +86,6 @@
 int: 1000
 bin: 0b11
 hex: 0x11
-oct: 0o11
 dec: .3
 dat: !!binary gA==
 nil: null
@@ -148,13 +146,13 @@
 		// TODO: support this at some point
 		name: "embed",
 		in: `
-	// octal
-	0o755 // line
+	// hex
+	0xabc // line
 	// trail
 	`,
 		out: `
-# octal
-0o755 # line
+# hex
+0xabc # line
 # trail
 `,
 	}, {