Some image name strings are exponential in parse times WRT length

[MrCreosote]

I'm not sure what's causing this so I'm sure this is only a fraction of the cases where this could occur, but there's certain image name strings that take exponentially longer to parse as a function of the name length:

In [1]: from docker_image import reference

In [2]: import time

In [3]: def test_char(name, char):
   ...:     try:
   ...:         t1 = time.time()
   ...:         reference.Reference.parse_normalized_named(f"{name}:0.15{char}.0
   ...: ")
   ...:     except reference.ReferenceInvalidFormat:
   ...:         return time.time() - t1
   ...: 

In [4]: namefull = "abcdefghijklmnopqrst"

In [7]: for ln in range(10, 21, 5):
   ...:     name = namefull[:ln]
   ...:     print(f"Name len: {len(name)}")
   ...:     for char in "[]$()`&|<>;,\n{}'\"":
   ...:         print(f"    {char} {test_char(name, char):0.2f}")
   ...:     print("\n")
   ...: 
Name len: 10
    [ 0.00
    ] 0.00
    $ 0.00
    ( 0.00
    ) 0.00
    ` 0.06
    & 0.00
    | 0.00
    < 0.00
    > 0.00
    ; 0.03
    , 0.00
    
 0.03
    { 0.00
    } 0.00
    ' 0.00
    " 0.00


Name len: 15
    [ 0.00
    ] 0.00
    $ 0.00
    ( 0.00
    ) 0.00
    ` 0.86
    & 0.00
    | 0.00
    < 0.00
    > 0.00
    ; 0.88
    , 0.00
    
 0.88
    { 0.00
    } 0.00
    ' 0.00
    " 0.00


Name len: 20
    [ 0.00
    ] 0.00
    $ 0.00
    ( 0.00
    ) 0.00
    ` 29.65
    & 0.00
    | 0.00
    < 0.00
    > 0.00
    ; 28.44
    , 0.00
    
 28.26
    { 0.00
    } 0.00
    ' 0.00
    " 0.00

In particular, the backtick, ;, and newline characters seem to cause major parse problems for the regex parser. I tried putting the characters into the name portion of the image string but that didn't seem to have the same effect. Possibly the proximity to . causes the issue...? I didn't test that.

[MrCreosote]

As a workaround prior to parsing I just run the regex r"([^a-zA-Z0-9@:_.\-\/])" and throw an error if it finds anything