TypeError: write() argument must be str, not list while writing to file

I wrote one program which help inrementing the digit in the file. Able to copy only first line if I am using writelines and for f.write I am getting
f.write(new_line ) if lines[0].strip().endswith(':') else f.write([new_line, *lines]) TypeError: write() argument must be str, not list

file.txt

Django 2.1:0
    djangoAPI1
    djangoAPI2

My Code

import re
regex = r'(?<=:)\d*$'
def incr_patch_version(fname):
    with open(fname, 'r+') as f:
        lines = f.readlines()
        #print  (lines[0])
        new_line = re.sub(regex, lambda x: str(int(x.group()) + 1 if x.group().isnumeric() else 0), lines[0])
        f.seek(0)
        print (*lines)
        f.write(new_line ) if lines[0].strip().endswith(':') else f.write([new_line, *lines])
        #f.write(new_line ) if lines[0].strip().endswith(':') else f.writelines([new_line, *lines])
fname = 'file.txt'
incr_patch_version(fname)

if I am using f.write(new_line ) if lines[0].strip().endswith(':') else f.writelines([new_line, *lines]). I am getting the below output

Django 2.1:3
Django 2.1:2
Django 2.1:1
Django 2.1:0
    djangoAPI1
    djangoAPI2

Desired Output file after 2 execution

Django 2.1:2
    djangoAPI1
    djangoAPI2        
Django 2.1:1
    djangoAPI1
    djangoAPI2        
Django 2.1:0
    djangoAPI1
    djangoAPI2

from TypeError: write() argument must be str, not list while writing to file