INSTALL: require Perl 5.26.0

Our platform support policy states that we require "versions of
dependencies which are generally accepted as stable and supportable,
e.g., in line with the version used by other long-term-support
distributions".  Of Debian, Ubuntu, RHEL, and SLES, the four most common
distributions that provide LTS versions, the version with mainstream
long-term security support with the oldest Perl is 5.26.0 in SLES 15.6.

This is a major upgrade, since Perl 5.8.1, according to the Perl
documentation, was released in September of 2003.  It brings a lot of
new features that we can choose to use, such as s///r to return the
modified string, the postderef functionality, and subroutine signatures,
although the latter was still considered experimental until 5.36.

Update the INSTALL file to reflect our new dependency requirement.

Signed-off-by: brian m. carlson <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: bk2204

INSTALL

@@ -119,7 +119,7 @@ Issues of note:
 	- A POSIX-compliant shell is required to run some scripts needed
 	  for everyday use (e.g. "bisect", "request-pull").
 
-	- "Perl" version 5.8.1 or later is needed to use some of the
+	- "Perl" version 5.26.0 or later is needed to use some of the
 	  features (e.g. sending patches using "git send-email",
 	  interacting with svn repositories with "git svn").  If you can
 	  live without these, use NO_PERL.  Note that recent releases of