ci: replace Jenkins with Gitea Actions, modernize DESCRIPTION

- Add real R CMD check workflow via Gitea Actions (rocker/r-ver:4.4)
- Remove Jenkinsfile and demo workflow
- Modernize DESCRIPTION: Authors@R, R >= 4.1.0, URL/BugReports fields,
  move tidycensus from Imports to Suggests, testthat edition 3
- Fix agresti_coull_interval: correct implementation, export it
- Convert get_fips/get_stabbr to use requireNamespace for tidycensus
- Remove civilytics:: self-reference in rnh()

DESCRIPTION

@@ -2,25 +2,29 @@ Package: civilytics
 Type: Package
 Title: Utilities Functions for Civilytics
 Version: 0.2.0
-Author: Jared E. Knowles <jared@civilytics.com>
-Maintainer: Jared E. Knowles <jared@civilytics.com>
-Description: House R functions for Civilytics Consulting LLC
-    This package implements a variety of useful functions for creating and 
-    branding analyses produced by Civilytics Consulting LLC. 
+Authors@R:
+    person("Jared", "E. Knowles", email = "jared@civilytics.com",
+           role = c("aut", "cre"))
+Description: House R functions for Civilytics Consulting LLC. This package
+    implements a variety of useful functions for creating and branding analyses
+    produced by Civilytics Consulting LLC.
 License: LGPL (>= 3)
+URL: https://gitea.civilytics.org/Civilytics/civilyticsR
+BugReports: https://gitea.civilytics.org/Civilytics/civilyticsR/issues
 Depends:
-    R (>= 2.15.1)
+    R (>= 4.1.0)
 Imports:
     ggplot2,
     jpeg,
     png,
     stringr,
     gridExtra,
-    tidycensus,
     grid,
     stringdist
 Encoding: UTF-8
 LazyData: true
-Suggests: 
-    testthat
+Suggests:
+    testthat (>= 3.0.0),
+    tidycensus
 RoxygenNote: 7.3.2
+Config/testthat/edition: 3