maint: Bump versions to begin active development of Octave 10.

* configure.ac (AC_INIT): Set version to 10.0.0.
(OCTAVE_MAJOR_VERSION): Now 10.
(OCTAVE_PATCH_VERSION): Now 0.

configure.ac

@@ -27,7 +27,7 @@ dnl
 
 ### Initialize Autoconf
 AC_PREREQ([2.65])
-AC_INIT([GNU Octave], [9.0.1], [https://octave.org/bugs.html], [octave],
+AC_INIT([GNU Octave], [10.0.0], [https://octave.org/bugs.html], [octave],
         [https://www.gnu.org/software/octave/])
 
 ### Declare version numbers
@@ -39,9 +39,9 @@ dnl AC_INIT requires it to be static, not computed from shell variables.
 ## explains how to update these numbers for release and development
 ## versions.
 
-OCTAVE_MAJOR_VERSION=9
+OCTAVE_MAJOR_VERSION=10
 OCTAVE_MINOR_VERSION=0
-OCTAVE_PATCH_VERSION=1
+OCTAVE_PATCH_VERSION=0
 
 dnl PACKAGE_VERSION is set by the AC_INIT VERSION argument.
 OCTAVE_VERSION="$PACKAGE_VERSION"