Разделите строку на основе двоеточия и новой строки и добавьте результат в словарь

Ваша непосредственная проблема - это двоеточие - вы можете решить это, используя line.split(':', 1)

У вас также будут проблемы с элементами списка. Входной файл случайно не yaml?

import yaml

data = """
Version: 67
Build Number: 123master
Project Name: git+ssh://[email protected]:1999/ns/x-y.git
Git Url: origin/master
Git Branch: 0223445as5njn34nfk6kg
perforce_url:
  //project//url//
artifacts:
  "./": "./"
exclude:
  - manifest.yml
  - node_modules
  - RPMS
  - .git
  - build-toolbox
"""
yaml.load(data)

Вы можете написать свой собственный парсер (например):

from parsimonious.grammar import Grammar
from parsimonious.nodes import NodeVisitor

data = """
Version: 67
Build Number: 123master
Project Name: git+ssh://[email protected]:1999/ns/x-y.git
Git Url: origin/master
Git Branch: 0223445as5njn34nfk6kg
perforce_url:
  //project//url//
artifacts:
  "./": "./"
exclude:
  - manifest.yml
  - node_modules
  - RPMS
  - .git
  - build-toolbox 

"""

grammar = Grammar(
    r"""
    entries     = (item / list / ws)+

    item        = key equal ws* (!listsep value) newline?

    list        = listkey listitem+
    listkey     = key equal hs* newline
    listitem    = hs* listsep hs* value newline?

    key         = ~"^[^:]+"m
    equal       = ":"
    listsep     = "-"
    value       = ~".+"

    ws          = (hs / newline)+
    newline     = ~"[\r\n]"
    hs          = ~"[\t ]+"
    """
)

tree = grammar.parse(data)

class YAMLVisitor(NodeVisitor):
    def generic_visit(self, node, visited_children):
        return visited_children or node

    def visit_key(self, node, visited_children):
        return node.text.strip()

    def visit_value(self, node, visited_children):
        return node.text.strip()

    def visit_listkey(self, node, visited_children):
        key, *_ = visited_children
        return key

    def visit_listitem(self, node, visited_children):
        *_, value, _ = visited_children
        return value

    def visit_list(self, node, visited_children):
        key, values = visited_children
        return (key, values)

    def visit_item(self, node, visited_children):
        key, *_, lst, nl = visited_children
        value = lst[1]
        return (key, value)

    def visit_entries(self, node, visited_children):
        output = dict([child[0] for child in visited_children if isinstance(child[0], tuple)])
        return output


yaml = YAMLVisitor()
output = yaml.visit(tree)
print(output)

{'Version': '67', 'Build Number': '123master', 'Project Name': 'git+ssh://[email protected]:1999/ns/x-y.git', 'Git Url': 'origin/master', 'Git Branch': '0223445as5njn34nfk6kg', 'perforce_url': '//project//url//', 'artifacts': '"./": "./"', 'exclude': ['manifest.yml', 'node_modules', 'RPMS', '.git', 'build-toolbox']}