interp: Add wasip1 to known OS list

Adds `wasip1` to known OS list, introduced in golang/go#58141.

Without this change, `yaegi extract` may fail on Go 1.21 with the following message:
```
type-checking package "time" failed (<GOROOT>/src/time/zoneinfo_wasip1.go:8:5: platformZoneSources redeclared in this block)
```

interp/build.go

@@ -182,6 +182,7 @@ var knownOs = map[string]bool{
  "openbsd": true,
  "plan9": true,
  "solaris": true,
+ "wasip1": true,
  "windows": true,
 }