bgpd: fix version attribute is an int, not a string (backport #17506)

[mergify]

The json display of the version attribute is originally an integer. It has changed, most probably mistakenly.

{
"vrfId": 7,
"vrfName": "vrf1",
"tableVersion": 3,
"routerId": "192.0.2.1",
"defaultLocPrf": 100,
"localAS": 65500,
"routes": {
"172.31.0.1/32": {
"prefix": "172.31.0.1/32",
"version": "1", <--- int or string ??

Let us fix it, by using the integer display instead.

Fixes: f9f2d18 ("bgpd: fix 'json detail' output structure")

---

This is an automatic backport of pull request #17506 done by Mergify.

[mergify]

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	both modified:   bgpd/bgp_route.c

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