python3-config: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/python3-config - from package: python3-dev

You may install the required package with command apt-get install {package}

Error in other languages:
python3-config: bevel nie gevind nie
python3-config: comandă negăsită
python3-config: comando não encontrado
python3-config: commande introuvable
python3-config: command not found
python3-config: käsku ei ole
python3-config: không tìm thấy lệnh
python3-config: komanda nerasta
python3-config: Kommando nicht gefunden.
python3-config: kommandot finns inte
python3-config: komut yok
python3-config: nie znaleziono polecenia
python3-config: níor aimsíodh an t-ordú
python3-config: no se encontró la orden
python3-config: no s'ha trobat l'ordre
python3-config: opdracht niet gevonden
python3-config: parancs nem található
python3-config: perintah tidak ditemukan
python3-config: príkaz nenájdený
python3-config: příkaz nenalezen
python3-config: команда не найдена
python3-config: командата не е открита
python3-config: 命令找不到
python3-config: コマンドが見つかりません