filetypes
должен быть кортежем кортежей. Например:
from tkinter import filedialog as fd
filename = fd.askopenfilename(title = "Select file",filetypes = (("CSV Files","*.csv"),))
Но я предлагаю вам сделать все аккуратно и в одном окне. Например, тот же ввод, что и у вас, но с опрятным значением:
from tkinter import *
from tkinter import filedialog as fd
def get_file_name(file_entry):
file_name = fd.askopenfilename(title = "Select file",filetypes = (("CSV Files","*.csv"),))
file_entry.delete(0,END)
file_entry.insert(0,file_name)
def run_and_close(event=None):
######################################
## EXECUTE OR CALL OTHER PYTHON FILE##
######################################
close()
def close(event=None):
master.withdraw() # if you want to bring it back
sys.exit() # if you want to exit the entire thing
master = Tk()
master.title("This is my Interface")
entry_csv=Entry(master, text="", width=50)
entry_csv.grid(row=0, column=1, sticky=W, padx=5)
Label(master, text="Input CSV").grid(row=0, column=0 ,sticky=W)
Button(master, text="Browse...", width=10, command=lambda:get_file_name(entry_csv)).grid(row=0, column=2, sticky=W)
Button(master, text="Ok", command=run_and_close, width=10).grid(row=3, column=1, sticky=E, padx=5)
Button(master, text="Cancel", command=close, width=10).grid(row=3, column=2, sticky=W)
master.bind('<Return>', run_and_close)
master.bind('<Escape>', close)
mainloop()