Fix remaining wsl_v5 whitespace findings (refs #61)

Insert the blank line wsl_v5 requires above `defer` and `go`
statements that share no variables with the statement above them.
Applied mechanically via `make lint-fix`; the diff is 60 added blank
lines and nothing else.

internal/snapshot/snapshot_test.go

@@ -25,12 +25,14 @@ func copyFile(fs afero.Fs, src, dst string) error {
 	if err != nil {
 		return err
 	}
+
 	defer func() { _ = sourceFile.Close() }()
 
 	destFile, err := fs.Create(dst)
 	if err != nil {
 		return err
 	}
+
 	defer func() { _ = destFile.Close() }()
 
 	_, err = io.Copy(destFile, sourceFile)
@@ -53,6 +55,7 @@ func verifyCleanedDB(
 	if err != nil {
 		t.Fatalf("failed to open cleaned database: %v", err)
 	}
+
 	defer func() {
 		err := cleanedDB.Close()
 		if err != nil {