Allow delays smaller than 50ms by setting delaybeforesend to None

Pexpect added[1] a default delay of 50ms before send, by default, to work
around an issue with passwords being echod.  This makes it impossible to have
delays smaller than this 50ms, currently.  This commit allows setting
delaybeforesend to None, which is recommended by Pexpect to remove this
additional delay hardcoded in Pexpect's code.

[1] - https://github.com/pexpect/pexpect/blob/master/pexpect/pty_spawn.py#L136-L150

.github/workflows/CI.yml

@@ -28,7 +28,7 @@ jobs:
         - name: Run regression tests
           run: |
             set enable-bracketed-paste off
-            python3 -m pytest
+            python3 -m pytest -v
 
         - name: Check module imports with isort
           run: |

asciinema_automation/script.py

@@ -51,6 +51,7 @@ def __init__(
         delay,
         standard_deviation,
         timeout,
+        delaybeforesend=50 / 1000.0,
     ):
         # Set members from arguments
         self.inputfile = inputfile
@@ -59,6 +60,7 @@ def __init__(
         self.delay = delay / 1000.0
         self.wait = wait / 1000.0
         self.standard_deviation = standard_deviation / 1000.0
+        self.delaybeforesend = delaybeforesend
 
         # Default values for data members
         self.expected = "\n"
@@ -147,6 +149,7 @@ def execute(self):
         )
         logger.info(spawn_command)
         self.process = pexpect.spawn(spawn_command, logfile=None)
+        self.process.delaybeforesend = self.delaybeforesend
 
         self.process.expect("\n")
         logger.debug(self.process.before)