Fix pip installation after CentOS 7 EOL

[red1452]

Fix pip installation after CentOS 7 EOL

CentOS Linux 7 reached end of life (EOL) on June 30, 2024. Approach for installing paramiko was changed to installation from the yum install python-paramiko instead of pip install paramiko.

Fix PXF regression tests (#108)

The 669d593f5047408bba143cdd06364e6d03937230 commit appeared in GPDB 6.27.1. This commit adds warning message if user tries to create a table with no columns.

The pxf_fdw_foreign_table regression test used such tables. This patch adds columns to these tables.

[red1452]

Tests fail because at GBPD commit was added. This commit adds warning message: "creating a table with no columns". Regression diff:

--- \/tmp\/build\/pxf_src\/fdw\/expected\/pxf_fdw_foreign_table\.out    2024-07-08 12:37:56.543370072 +0000
+++ \/tmp\/build\/pxf_src\/fdw\/results\/pxf_fdw_foreign_table\.out     2024-07-08 12:37:56.547370060 +0000
@@ -33,6 +33,7 @@
 CREATE FOREIGN TABLE pxf_fdw_test_table ()
     SERVER pxf_fdw_test_server
     OPTIONS ( config '/foo/bar' );
+WARNING:  creating a table with no columns.
 ERROR:  the config option can only be defined at the pg_foreign_server level
 --
 -- Table creation succeeds if delimiter is provided with a single one-byte char
@@ -167,6 +168,7 @@
 CREATE FOREIGN TABLE pxf_fdw_test_table_csv_only ()
     SERVER pxf_fdw_test_server
     OPTIONS ( resource '/foo', quote '9' );
+WARNING:  creating a table with no columns.
 ERROR:  quote available only in CSV mode
 --
 -- Table creation fails if disable_ppd is non-boolean
@@ -174,6 +176,7 @@
 CREATE FOREIGN TABLE pxf_fdw_test_table_disable_ppd ()
     SERVER pxf_fdw_test_server
     OPTIONS ( resource '/ppd', disable_ppd '6' );
+WARNING:  creating a table with no columns.
 ERROR:  disable_ppd requires a Boolean value
 --
 -- Table creation succeeds if resource is provided and reject_limit is provided correctly

======================================================================

[RekGRpth]

Tests fail because at GBPD commit was added. This commit adds warning message: "creating a table with no columns". Regression diff:

--- \/tmp\/build\/pxf_src\/fdw\/expected\/pxf_fdw_foreign_table\.out    2024-07-08 12:37:56.543370072 +0000
+++ \/tmp\/build\/pxf_src\/fdw\/results\/pxf_fdw_foreign_table\.out     2024-07-08 12:37:56.547370060 +0000
@@ -33,6 +33,7 @@
 CREATE FOREIGN TABLE pxf_fdw_test_table ()
     SERVER pxf_fdw_test_server
     OPTIONS ( config '/foo/bar' );
+WARNING:  creating a table with no columns.
 ERROR:  the config option can only be defined at the pg_foreign_server level
 --
 -- Table creation succeeds if delimiter is provided with a single one-byte char
@@ -167,6 +168,7 @@
 CREATE FOREIGN TABLE pxf_fdw_test_table_csv_only ()
     SERVER pxf_fdw_test_server
     OPTIONS ( resource '/foo', quote '9' );
+WARNING:  creating a table with no columns.
 ERROR:  quote available only in CSV mode
 --
 -- Table creation fails if disable_ppd is non-boolean
@@ -174,6 +176,7 @@
 CREATE FOREIGN TABLE pxf_fdw_test_table_disable_ppd ()
     SERVER pxf_fdw_test_server
     OPTIONS ( resource '/ppd', disable_ppd '6' );
+WARNING:  creating a table with no columns.
 ERROR:  disable_ppd requires a Boolean value
 --
 -- Table creation succeeds if resource is provided and reject_limit is provided correctly

======================================================================

may add some words about it to description?