Upgrade to Go 1.20 (#4690)

Author: nwt

CONTRIBUTING.md

@@ -17,7 +17,7 @@ in [runtime/expr/agg](runtime/expr/agg).
 
 ## Development
 
-`zed` requires Go 1.19 or later, and uses [Go modules](https://github.com/golang/go/wiki/Modules).
+`zed` requires Go 1.20 or later, and uses [Go modules](https://github.com/golang/go/wiki/Modules).
 Compilation for 32-bit target environments is not currently supported
 (see [zed/4044](https://github.com/brimdata/zed/issues/4044)).
 Dependencies are specified in the [`go.mod` file](./go.mod) and fetched

docs/install.md

@@ -48,7 +48,7 @@ go install github.com/brimdata/zed/cmd/{zed,zq}@latest
 This installs the `zed` and `zq` binaries in your `$GOPATH/bin`.
 
 > If you don't have Go installed, download and install it from the
-> [Go install page](https://golang.org/doc/install). Go 1.19 or later is
+> [Go install page](https://golang.org/doc/install). Go 1.20 or later is
 > required.
 
 Once installed, run a [quick test](#quick-tests).

go.mod

@@ -1,6 +1,6 @@
 module github.com/brimdata/zed
 
-go 1.19
+go 1.20
 
 require (
 	github.com/agnivade/levenshtein v1.1.1