Allow static guid calls

[prolic]

Allow static calls to Guid::uuid4() and others

see #306

Maybe that's not the very best approach, but it should do the trick.

[prolic]

If you don't like this and want to block static calls on Guid instead, maybe you should also consider removing (or deprecating for now) those static methods from Uuid class as well. To me this would be kind of weird to have Uuid::uuid4() allowed but Guid::uuid4() not. If you have to go through the UuidFactory to create those, this should be the case for all then.

[ramsey]

I'm giving more thought to this. At first, I wanted to restrict calls to these static methods on the inheriting classes, but I'm giving this a second thought and will let you know soon. Thanks!

[codecov]

Codecov Report

Merging #307 (bd43e91) into 4.x (01433b5) will decrease coverage by 0.11%.
The diff coverage is 88.23%.

@@             Coverage Diff              @@
##                4.x     #307      +/-   ##
============================================
- Coverage     95.53%   95.42%   -0.12%     
- Complexity      554      557       +3     
============================================
  Files            64       64              
  Lines          1479     1485       +6     
============================================
+ Hits           1413     1417       +4     
- Misses           66       68       +2     

Impacted Files	Coverage Δ
src/Guid/Guid.php	75.00% <66.66%> (-25.00%)	⬇️
src/Uuid.php	96.51% <100.00%> (ø)