build: modernize Go usage

This commit modernizes Go usage. This was done with:

go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./...

Then files needed to be `go fmt`ed and a few comments needed to be
restored.

The modernizations include replacing

- if/else conditional assignment by a call to the built-in min or max functions added in go1.21
- sort.Slice(x, func(i, j int) bool) { return s[i] < s[j] } by a call to slices.Sort(s), added in go1.21
- interface{} by the 'any' type added in go1.18
- append([]T(nil), s...) by slices.Clone(s) or slices.Concat(s), added in go1.21
- loop around an m[k]=v map update by a call to one of the Collect, Copy, Clone, or Insert functions from the maps package, added in go1.21
- []byte(fmt.Sprintf...) by fmt.Appendf(nil, ...), added in go1.19
- append(s[:i], s[i+1]...) by slices.Delete(s, i, i+1), added in go1.21
- a 3-clause for i := 0; i < n; i++ {} loop by for i := range n {}, added in go1.22

backend/googlephotos/albums.go

@@ -4,6 +4,7 @@ package googlephotos
 
 import (
 	"path"
+	"slices"
 	"strings"
 	"sync"
 
@@ -119,7 +120,7 @@ func (as *albums) _del(album *api.Album) {
 		dirs := as.path[dir]
 		for i, dir := range dirs {
 			if dir == leaf {
-				dirs = append(dirs[:i], dirs[i+1:]...)
+				dirs = slices.Delete(dirs, i, i+1)
 				break
 			}
 		}

backend/googlephotos/googlephotos.go

@@ -388,7 +388,7 @@ func (f *Fs) fetchEndpoint(ctx context.Context, name string) (endpoint string, e
 		Method:  "GET",
 		RootURL: "https://accounts.google.com/.well-known/openid-configuration",
 	}
-	var openIDconfig map[string]interface{}
+	var openIDconfig map[string]any
 	err = f.pacer.Call(func() (bool, error) {
 		resp, err := f.unAuth.CallJSON(ctx, &opts, nil, &openIDconfig)
 		return shouldRetry(ctx, resp, err)
@@ -448,7 +448,7 @@ func (f *Fs) Disconnect(ctx context.Context) (err error) {
 			"token_type_hint": []string{"access_token"},
 		},
 	}
-	var res interface{}
+	var res any
 	err = f.pacer.Call(func() (bool, error) {
 		resp, err := f.srv.CallJSON(ctx, &opts, nil, &res)
 		return shouldRetry(ctx, resp, err)