report_participants: gender supports alternate spellings, convert age to numeric

[rempsyc]

report_participants: gender supports alternate spellings, convert age to numeric

---

Fixes #388:

library(report)
data <- data.frame(
  "Age" = as.character(c(22, 22, 28, 11, 42, 52)),
  "Gender" = c("Men", "Women", "Men", "Women", "Men", "Women")
)
report_participants(data)
#> [1] "6 participants (Mean age = 29.5, SD = 15.0, range: [11, 52]; Gender: 50.0% women, 50.0% men, 0.00% non-binary)"

^{Created on 2023-08-18 with reprex v2.0.2}

[codecov]

Codecov Report

Merging #389 (b533df8) into main (0b1046d) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head b533df8 differs from pull request most recent head e7e1e94. Consider uploading reports for the commit e7e1e94 to get more accurate results

@@            Coverage Diff             @@
##             main     #389      +/-   ##
==========================================
+ Coverage   72.25%   72.27%   +0.01%     
==========================================
  Files          47       47              
  Lines        3316     3329      +13     
==========================================
+ Hits         2396     2406      +10     
- Misses        920      923       +3     

Files Changed	Coverage Δ
R/report_participants.R	93.10% <100.00%> (+0.32%)	⬆️

... and 1 file with indirect coverage changes