Modernize container and add dependencies

[pbchase]

Address missing mRpostman and Debian package dependencies.

Container build is still failing with

 > [ 8/21] RUN R CMD build redcapcustodian:                                                                                 
#12 1.396 * checking for file ‘redcapcustodian/DESCRIPTION’ ... OK                                                          
#12 1.500 * preparing ‘redcapcustodian’:                                                                                    
#12 1.502 * checking DESCRIPTION meta-information ... OK                                                                    
#12 1.991 * installing the package to build vignettes                                                                       
#12 12.11 * creating vignettes ... ERROR
#12 21.01 --- re-building ‘credential-scraping.Rmd’ using rmarkdown
#12 21.01 Killed
#12 21.01 Warning in system(paste(shQuote(path), "--version"), intern = TRUE) :
#12 21.01   running command ''/usr/local/bin/pandoc' --version' had status 137
#12 21.01 Error: processing vignette 'credential-scraping.Rmd' failed with diagnostics:
#12 21.01 subscript out of bounds
#12 21.01 --- failed re-building ‘credential-scraping.Rmd’
#12 21.01 
#12 21.01 --- re-building ‘expire_user_project_rights.Rmd’ using rmarkdown
#12 21.01 Killed
#12 21.01 Warning in system(paste(shQuote(path), "--version"), intern = TRUE) :
#12 21.01   running command ''/usr/local/bin/pandoc' --version' had status 137
#12 21.01 Error: processing vignette 'expire_user_project_rights.Rmd' failed with diagnostics:
#12 21.01 subscript out of bounds
#12 21.01 --- failed re-building ‘expire_user_project_rights.Rmd’
#12 21.01 
#12 21.01 SUMMARY: processing the following files failed:
#12 21.01   ‘credential-scraping.Rmd’ ‘expire_user_project_rights.Rmd’
#12 21.01 
#12 21.01 Error: Vignette re-building failed.
#12 21.01 Execution halted