Convert some regex strings to raw format

Using Python 3.12.0 for `dev/run` gives these warnings:
```
❯ dev/run -a adm:pass --with-haproxy --no-eval REMSHID=1 dev/remsh
/Users/jay/repos/couchdb/dev/run:534: SyntaxWarning: invalid escape sequence '\d'
  JAVA_VERSION_RE = re.compile('"(\d+\.\d+).*"')
/Users/jay/repos/couchdb/dev/run:686: SyntaxWarning: invalid escape sequence '\['
  "^\[httpd\]$",
/Users/jay/repos/couchdb/dev/run:694: SyntaxWarning: invalid escape sequence '\['
  "^\[native_query_servers\]$",
```
This changes the strings in question to "raw" format, and eliminates
the warnings.
diff --git a/dev/run b/dev/run
index 85f8b65..fcafcf5 100755
--- a/dev/run
+++ b/dev/run
@@ -531,7 +531,7 @@
 
 
 CLOUSEAU_DIR = "clouseau"
-JAVA_VERSION_RE = re.compile('"(\d+\.\d+).*"')
+JAVA_VERSION_RE = re.compile(r'"(\d+\.\d+).*"')
 
 
 def get_java_version(java):
@@ -683,7 +683,7 @@
 
 def hack_default_ini(ctx, node, contents):
     contents = re.sub(
-        "^\[httpd\]$",
+        r"^\[httpd\]$",
         "[httpd]\nenable = true",
         contents,
         flags=re.MULTILINE,
@@ -691,7 +691,7 @@
 
     if ctx["enable_erlang_views"]:
         contents = re.sub(
-            "^\[native_query_servers\]$",
+            r"^\[native_query_servers\]$",
             "[native_query_servers]\nerlang = {couch_native_process, start_link, []}",
             contents,
             flags=re.MULTILINE,