Bump required python version to 3.6.

We currently use f-strings in some of the test tools.  These are
supported only starting with python version 3.6.

Given that python version 3.4 is EOL since March 2019, it's about
time to bump the required version to 3.6:

https://www.python.org/downloads/release/python-3410/

Signed-off-by: Dumitru Ceara <dceara@redhat.com>
Acked-by: Mark Michelson <mmichels@redhat.com>

NEWS

@@ -1,5 +1,17 @@
 OVN v22.03.2 - xx xxx xxxx
 --------------------------
+  - Bump python version required for building OVN to 3.6.
+
+OVN v22.06.0 - 03 Jun 2022
+--------------------------
+  - Support IGMP and MLD snooping on transit logical switches that connect
+    different OVN Interconnection availability zones.
+  - Replaced the usage of masked ct_label by ct_mark in most cases to work
+    better with hardware-offloading.
+  - Support NAT for logical routers with multiple distributed gateway ports.
+  - Add global option (NB_Global.options:default_acl_drop) to enable
+    implicit drop behavior on logical switches with ACLs applied.
+>>>>>>> 6cbda808a (Bump required python version to 3.6.)
   - Support (LSP.options:qos_min_rate) to guarantee minimal bandwidth available
     for a logical port.
 

m4/ovn.m4

@@ -300,7 +300,7 @@ dnl Checks for valgrind/valgrind.h.
 AC_DEFUN([OVN_CHECK_VALGRIND],
   [AC_CHECK_HEADERS([valgrind/valgrind.h])])
 
-dnl Checks for Python 3.4 or later.
+dnl Checks for Python 3.6 or later.
 AC_DEFUN([OVN_CHECK_PYTHON3],
   [AC_CACHE_CHECK(
      [for Python 3 (version 3.4 or later)],
@@ -309,13 +309,13 @@ AC_DEFUN([OVN_CHECK_PYTHON3],
         ovs_cv_python3=$PYTHON3
       else
         ovs_cv_python3=no
-        for binary in python3 python3.4 python3.5 python3.6 python3.7; do
+        for binary in python3 python3.4 python3.5 python3.6 python3.7 python3.8 python3.9 python 3.10; do
           ovs_save_IFS=$IFS; IFS=$PATH_SEPARATOR
           for dir in $PATH; do
             IFS=$ovs_save_IFS
             test -z "$dir" && dir=.
             if test -x "$dir"/"$binary" && "$dir"/"$binary" -c 'import sys
-if sys.hexversion >= 0x03040000 and sys.hexversion < 0x04000000:
+if sys.hexversion >= 0x03060000 and sys.hexversion < 0x04000000:
     sys.exit(0)
 else:
     sys.exit(1)'; then
@@ -326,7 +326,7 @@ else:
         done
       fi])
    if test "$ovs_cv_python3" = no; then
-     AC_MSG_ERROR([Python 3.4 or later is required but not found in $PATH, please install it or set $PYTHON3 to point to it])
+     AC_MSG_ERROR([Python 3.6 or later is required but not found in $PATH, please install it or set $PYTHON3 to point to it])
    fi
    AC_ARG_VAR([PYTHON3])
    PYTHON3=$ovs_cv_python3])