[Bug]: as.POSIXlt: character string is not in a standard unambiguous format

### What happened?

There seems to be a problem with the min_cohort strategy:

```r
pkg_path <- "teal.modules.hermes"
min_cohort <- new_min_cohort_deps_installation_proposal(pkg_path)
## Error in as.POSIXlt.character(x, tz, ...) :
## character string is not in a standard unambiguous format
```

I'm using R 4.5.2

### Which version(s) of R were you using?

_No response_

### Relevant log output

```R
traceback()
18: stop("character string is not in a standard unambiguous format")
17: as.POSIXlt.character(x, tz, ...)
16: as.POSIXlt(x, tz, ...)
15: as.POSIXct(as.POSIXlt(x, tz, ...), tz, ...)
14: as.POSIXct.default(value)
13: as.POSIXct(value)
12: `[<-.POSIXct`(`*tmp*`, ri, value = "1770108623")
11: `[<-`(`*tmp*`, ri, value = "1770108623")
10: rbind(deparse.level, ...)
9: rbind(cran_archive, cran_current) at get_ref.R#576
8: get_release_data(remote_ref$package) at get_ref.R#477
7: get_release_date.remote_ref_cran(remote_ref) at get_ref.R#502
6: get_release_date.remote_ref_standard(remote_ref) at get_ref.R#431
5: get_release_date(remote_ref) at get_ref.R#592
4: get_avail_date(i_ref_ver) at deps_installation_proposal.R#200
3: FUN(X[[i]], ...)
2: lapply(seq_len(nrow(deps)), function(i) {
i_pkg <- deps[i, "package"]
if (tolower(deps[i, "type"]) %nin% dependencies_config_cache) {
return(NA)
}
if (i_pkg %in% base_pkgs()) {
return(NA)
}
if (i_pkg %nin% refs_pkg) {
return(NA)
}
i_ref <- refs[[which(refs_pkg == i_pkg)]]
i_ver <- deps[i, "version"]
version <- version_from_desc(d, i_ref$package)
i_ref_ver <- get_ref_min(i_ref, version$op, version$op_ver)
get_avail_date(i_ref_ver)
}) at deps_installation_proposal.R#178
1: new_min_cohort_deps_installation_proposal(pkg_path)
```

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