fix(shmigrate): use errors.Is for fs.ErrNotExist compatibility

os.IsNotExist does not recognize fs.ErrNotExist when wrapped by an
fs.FS implementation. Switch to errors.Is(err, fs.ErrNotExist) so
the "file not found" check works for both os.Open and fs.FS.Open.

database/sqlmigrate/shmigrate/go.mod

@@ -2,6 +2,4 @@ module github.com/therootcompany/golib/database/sqlmigrate/shmigrate
 
 go 1.26.1
 
-require github.com/therootcompany/golib/database/sqlmigrate v0.0.0
+require github.com/therootcompany/golib/database/sqlmigrate v1.0.0
-
-replace github.com/therootcompany/golib/database/sqlmigrate => ../

database/sqlmigrate/shmigrate/go.sum

@@ -0,0 +1,2 @@
+github.com/therootcompany/golib/database/sqlmigrate v1.0.0 h1:vehFGUBdv/su0jDzSNxYN7N7i1KE3l2QJDf4x9LXhwQ=
+github.com/therootcompany/golib/database/sqlmigrate v1.0.0/go.mod h1:7PQUjwT78Hx+SftcIKI2PH4zSFlrSO0V9h618PJqC38=

database/sqlmigrate/shmigrate/shmigrate.go

@@ -6,6 +6,7 @@ package shmigrate
 import (
 	"bufio"
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"io/fs"
@@ -103,7 +104,7 @@ func (r *Migrator) Applied(ctx context.Context) ([]sqlmigrate.AppliedMigration,
 		f, err = os.Open(r.LogPath)
 	}
 	if err != nil {
-		if os.IsNotExist(err) {
+		if errors.Is(err, fs.ErrNotExist) {
 			return nil, nil
 		}
 		return nil, fmt.Errorf("reading migrations log: %w", err)